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.

Example of subtracting fractions with unlike denominators

Discussion and questions for this video
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
Can't you just check if the numerator is prime? that way you wouldn't have to divide 19 into 156.
Of course you can! But most people don't know prime numbers after 101 . . . and it's usually a factorable number anyway.
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
He did it to make shure 19 fight into 156 if it did fight he would have simplified it
Can you use the up and down way while subtracting fractions? 9
Also can you do it an easier way? + 8
For your 1st question, yes, and the 2nd one..well in my opinion long way is easier.
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!!
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
What if one of the numerators are equal to each and make zero what would happen then?
So all you have to do is multiply then subtract? Would that be mathmatically correct or still wrong?
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 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.
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.

Hope this was helpful
how come when i was doing the question with him i got a repating dectimal
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.
And what if a fraction has a numerator bigger than the denominator. For example. 6/2 - 7/4?
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!
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.
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
why is it that big of a number, when ur just subtracting those little number... it's like your adding instead of subtracting!
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)
3) asking specific questions about what you don't understand

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.
😲what happens if the denominator?do you need to add/subtract both of the denominator?😵
it is depend all on multiplication ,division,subtraction and addition
What if the numerator for the first fraction has a greater number than the second fraction? 21>5
Saying 21 is the first fraction over whatever it could be, and it's subtracting.
Do you always have to times the denominator by the other denominator to get a common denominator?
Well, sometimes you don't have to. For example, if you have
5/12 + 1/6, you don't need to multiply 12 and 6. You just need to find a number that they both go into. If you did multiply them together, you'd follow the steps below:
5/12 + 1/6
5*6/12*6 + 1*12/6*12 = 30/72 + 12/72
30+12=42, so 42/72
Simplified = 7/12
If you wanted to, you could also have used 60, because both 12 and 6 can go into 60. (12 times 5, and 6 times 10). Then you'd do the steps below:
5/12 + 1/6
5*5/12*5 + 1*10/6*10 = 25/60 + 10/60
25+10=35, so 35/60
Simplified = 7/12
Either way works! Usually it easiest to just multiply, but if you're dealing with big numbers it could get messy and then you should find the lowest number possible that they both fit in to make it more simple. Hope this helps!
what if you want to subtract a number like 1/4-1/3 where they have a LCM but the first number is smaller than the second number is it just a negative, thx
first we should multiply the numerator of first fraction to the denominator of second fraction.then multiply second fraction's numerator to the first fraction's denominator.then multiply both fractions denominator.
for example :- 2/5 - 6/3 = 6/15 -30/15 = -24/15
Try watching the video again slowly, taking notes (if that helps you). As your parents for help, and you can ask more specific questions here.
why do we make the steps that we make
I liked this video but on I was wondering if you could show me subtracting fractions with different denominators vertically
Change 16/7 to a mixed number which is 2 2/7, then find an equal denominator and finally subtract.
Why do we need to do to numerator that you did in the denominator? ( multiplication)
Isn't there a easier way of doing this? Because I thought all we have to do is find the least common denominator then multiply that with the numerator, finally we add them and then we have the answer. I s that not correct?
Ok, basically in order to subtract the fractions they have to have identical denominators. In order to do that he is multiplying the numerator and denominator of one fraction by the denominator of the other. You can keep a fraction as having the same value as long as it is multiplied by 1. Any number divided by itself is 1, so 12/12 = 1 and 13/13 is 1. He doesn't simplify it into that of course just so he can actually perform the subtraction
7 6
-- - --
12 13
Multiply both of the fractions by 1
7 1 6 1
-- X - - -- X -
12 1 13 1
I'm just going to do each one individually for the moment
7 7 1 7 13 7 X 13 91
-- = -- X - = -- X -- = ------- = ---, I did the 13/13 as that's the denominator of the other fraction
12 12 1 12 13 12 X 13 156

6 6 1 6 12 6 X 12 72
-- = -- X - = -- X -- = ------- = ---, I did the 13/13 as that's the denominator of the other fraction
13 13 1 13 12 13 X 12 156

Going back to the problem
7 6 7 X 13 6 X 12 91 72 91 - 72 19
-- - -- = ------- - ------- = --- - --- = ------- = ---
12 13 12 X 13 13 X 12 156 156 156 156
First, you divide 44/28 on both sides by their GCF, which is 4. 44/4 is 11 and 28/4 is 7.
So, the simplified fraction is 11/7, or 1 4/7.
Some do share a common denominator for instance 2&5 do share a common denominator 10 sorry again 4 the confusion.