Fractions

# Adding and subtracting fractions with unlike denominators

## Example of subtracting fractions with unlike denominators

If you conquered adding fractions with different denominators, then subtracting fractions will be a snap. Don't worry...we'll take it slow and explain every step.
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## Example of subtracting fractions with unlike denominators

Discussion and questions for this video
Why do you have to make the denominaters the same
u have to do that in order to answer the question.If u dont find the LCD or the common denominator then ur answer would be wrong
Pls suggest to subtract 7/10 from 11/12
11/12 - 7/10 = 13/60
That's a good method, but it takes too long, I mean you have to solve many problems in order to solve one, is there another way?
same. also don't think there is another way to answer it.
thank you for helping me this is really useful
Thank you for helping me, this is really uesful!
Why do you have to make the denominators the same? Can't you just subtract the numerators and the denominators?
89-67=78
67-86=89
76 -89=86
i need more help on fractions
How learn the multiplication
By listeing dedicated subjects
how do you multiply with diffrent denominator?
1 Comment
The denominators stay the same. It also goes with division.
thanks helped a lot
love math alot
math is too hard i get frustrated
Don't worry, eventually you'll get the answer, and you'll feel so great because you're so smart! Don't feel down because math is hard, because if you try enough, you will get it and it will be the best thing in the world! Good luck! :D
but 7-6 is 1 so it should be 1/156
you make these vids so complicated
But you forgot that you need to multiply 13 to 7 and 12 to 6 in order for the fraction to stay the same and not ruin the equation, that's why its 91-72 which is equals to 19. If its still vague i can give an example
I don't get the part at the end dividing it because on my sum I divided and I got an answer and now I have know idea what to do and I have to sign it in toady at 2 pm
and cookiedough313 my mom says keep practicing and you'll get better at it!
manmanolseki you spelled today wrong!
Why do you have to make the denominators the same? Can't you just subtract the numerators and the denominators?
No, you can't, because you can't subtract unlike fractions
tis is REALLY confusing
no it isent. it is helpful
Can you use the up and down way while subtracting fractions? 9
Also can you do it an easier way? + 8
______
17
For your 1st question, yes, and the 2nd one..well in my opinion long way is easier.
what 1 whole and 2/4 minus 3/4
1 2/4 = 6/4
6/4 - 3/4 = 3/4
Why are you suppose to make the denominater the same?
when adding or subtracting fractions, you need to have a like denominator, or the same denominator, because that way, the answer won't have a completely different denominator. example: 2/5-1/3
you shouldn't just leave the denominators the way they are and subtract them from each other, because then you will have the answer 1/2
what is a fraction
it is when the denominator is greater than the numerator
Yes, just like 20/80 equals 1/4. When the numerator is 1, (like 1.2,) it cannot be simplified anymore. If, for example, 5/6 is your fraction you simplified, it cannot be simplified anymore either, because the numerator is one away from the denominator. I hope this helps!!
How do i subtract 7 3/10 from 2 3/4
First of all, we would convert the mixed numbers to improper fractions:
11/4 - 73/10
Then we would find a like multiple of the denominators, 4 and 10, such as 20. 20/4 is 5, so we'd multiply the numerator and denominator by 5, to get 55/20. 20/10 is 2, so we'd multiply the numerator and denominator of 73/10 by 2, to get 146/20. Our final problem:
55/20 - 146/20 = -91/20
This guy is so confusing!
do you have a specific question that I could answer for you?
What is 9 over 10 take away 1 over 2
1 Comment
2/5 which is two over five.
I don't get about the thing in the end..
So what he did near the end was combine the two fractions into a fraction with a like denominator and the two different numerators that are being subtracted., because only numerators can be subtracted.
Sorry this is late but hope this helps
do you do this method Sal to the addition,subtraction and,multiplication?
Ya what they said
What if one of the numerators are equal to each and make zero what would happen then?
how do I get like a 100 on all my math teas then
Study! study! study!
So all you have to do is multiply then subtract? Would that be mathmatically correct or still wrong?
it would be mathematically correct
Thank you for the video it was very helpful.

-Aviona Hoskins
do we always have to do it that way?.
yes.this is the only way to do it!!
Is there an easier, less complicated way to do this?
Yes.
example: 1/2-1/4=?
Explanation: do this
2X2=4 1X2=2
Easier way: 2/4-1/4
Hope i Helped you
That's really complicated. Is there by any chance an easier/simpler way to do this?
At 2:44, where did he get 72 from?
He does it so visual learners can understand better
I really still don't get it...
http://www.mathsisfun.com/fractions_subtraction.html
It explains how to subtract unlike and like denominator fractions.
whats 9 plus 10
are you the owner on KHAN!
The person talking in the video (which is Sal Khan) is the owner of Khan Academy
So can you talk a little bit slower
i was doing my homework and i got all of them doing that tecneek
That's good because you practiced really hard. Practice makes perfect.
it is kind of confusing for me
nevermind i get it now
at 0:43 why did he put the dots as multiplication signs if there is no algebra?
It doesn't have to be algebra when you are using dots as multiplication signs. You can sue a dot as the sign anywhere in a multiplication problem, its just that most people use an x as the multiplication sign before they reach algebra.
this is every thing I new I thot you were better.
can you please explain more because i don't get it at all. like how to divide
Oh it is easy. First take any fraction(9/13) and divide it by(3/4). All you need to do is take the reciprocal of the second no.(3/4)and multiply both of them. If you can simplify do it.

how come when i was doing the question with him i got a repating dectimal
could you explain the whole prossess of this and vote on it
thank you and sorry for bad spelling
The way it compares cause it is all math and it is fractions just sith diffrend botton numbers
What if the numerator is lower than what you are subtracting by like 5/10 - 8/17? Please help!
Well, in this example you will need to find a common denominator. For simplicity we will use 170. So the problem you gave really comes out to 85/170 - 80/170. The answer becomes 5/170 or 1/34.
If you mean what happens when the fraction that you are subtracting by is lower than the other fraction, well, then you would have a negative answer.
yeah its confusing if u don't do one with an lcm
you probably dont know the answer
And what if a fraction has a numerator bigger than the denominator. For example. 6/2 - 7/4?
You would do that in pretty much the same way.
What if the number is improper?
If the fraction is improper you turn it into a mixed number
I still don't understand it.
Basically, you just need to make this problem that you don't know how to solve into one that you do know how to solve. You just need to make the denominators (the bottom numbers) the same.

EX: 1/2 - 2/4
STEP 1) We know that 2 is half of 4, so 2/4 is actually just 1/2.
STEP 2) 1/2 - 1/2 = 0

I hope this helps!
6 3/12 - 3 9/36
you have to make the denominators "like" before you can do anything else. you have to find the LCM (Lowest Common Multiple) which makes the denominators equal. hope this is of any help to you :)
How do you solve a fraction with one whole number and the other number another fraction Ex: 1 and 3/20- 9/10?
1 3/20 is same as 20/20 + 3/20 which makes 23/20, now substracting 9/10 can be by giving the same nominator, so 9/10 is same as 18/20, 23/20 - 18/20 = 5/20 = 1/4
If at an election 6/9 of the members voted and there are 171 members how many people actually voted? Not sure how to work this problem.
I don't get it can someone explain it?
Shure be glad too say we need to subtract 1/2 -1/4 first we need to get them to the same denominator by multiplying the numerator and the denominator by 2 to get 2/4-1/4 which is now a very simple fraction problem.
Hope this helped.
and good luck.
well for thelove off pizza, of course you need to get the lowest common denominator, it says it in the title
How do you add and subtract positive and negative fractions with different denominators
thank you so much
why is it that big of a number, when ur just subtracting those little number... it's like your adding instead of subtracting!
don't know bro
I don't understand this at all can some one please explain this to me?
Hello Hannah, if you find yourself frustrated or confused by a topic or what Sal says in the video, you may try either:

1) rewatching the video, pausing and repeating confusing parts
2) reading through the questions and answers in here (some might contain the little bit you're missing)

Good luck!
How do you figure out 4 cups of flour and you need to use 1 3/4 cups for a recipe. How much do you have left?
We can make that problem easier by estimating a bit to get the whole number portion of the question out of the way. We know you are using 1 whole cup and part of another, so lets round up to 2 cups being used and subtract them from the initial 4 cups, which means that we know for sure there are at least 2 whole cups remaining.

After taking those off the question is now how much is left of the remaining 2 cups if we take 1 3/4 cup away. We can subtract out that whole cup used from both values leaving us with 1 cup - 3/4 cup which is a much easier problem to figure out.

We then take the answer to that and add it back in with the other 2 whole cups we had already determined would be left over.
Can you talk a little bit more happy
i still do not get it like 9/12-3/24
Make sure the denominators are equal. What times 12 equals 24?
Is there any simpler way to do this?
is there a easier way to multiply the denominator?
i don't think so
😲what happens if the denominator?do you need to add/subtract both of the denominator?😵
the denominator is something you do not change you only do the top number?
yep. the denominator and the other ones too
it is depend all on multiplication ,division,subtraction and addition