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# One-step addition & subtraction equations

Learn how to solve one-step addition and subtraction equations by adding or subtracting the same thing from both sides of the equation. Created by Sal Khan.

## Want to join the conversation?

• How do I setup an equation like 44-q=11 It's simply a true/false answer in my pre-algebra book. The answer is simple, it's 33. However, I don't know how to setup the equation. The example in the video shows the variable minus the number equals the difference. But what about when the number is first and the variable is subtracted from the number? How can I set up this equation so that future equations that cannot simply be solved without showing work can be solved?
• Hey try to do this if you get 44-q=11 it you have to set it up like this at he set it up like this that x+7=10. but one thing you have to remember is that if you have addition then you subtract and if you have subtraction than you have to add. in the x plus seven is equal to ten then you have to make a zero pair out of 7 so it equals to x and then you have to make the scale balance whatever you do the left side you have to on the right and subtract 10-7 which equals to 3 so you have to double like sal did in the first problem so he said this" 3+7 is indeed equal to 10.
• why on earth is a picture of the queen of england in this video?
• Hi Tianna!

Great question! I think the reason for the Queen of England is because Sal just thought "NO" to logic

Hope this helps =)
• Why is queen elizabeth teaching me math
• haha I'm not sure, but I really like that she is randomly there xD
• What is the Queen Elizabeth picture for?
• Half the questions on this video are "WHY IS THE QUEEN OF ENGLAND THERE" Who knows. No one knows for sure. And we may never know.
• Can someone please tell me why the queen is in the video? It's hilarious and it pushes me on. It's like she is saying, "Do your algebra by the order of the queen!". I'm just laughing inside.
• Why is the 5 considered to be a 'negative'? The way I read the equation, isn't it A, minus a positive number (n this case, 5)? And yet, Sal treats it as a negative number when balancing the equation. If it was supposed to be negative, should it not have read a - (-5) = -2?
• The thing with negatives, is that the dash in front of it is a minus sign. If it is a positive number, there is actually a plus sign in front of it, but we don't use it (but it's still there). This also happens with the negative. It's a minus sign.

I understand why you thought it was a positive (I thought it was positive as well before).

The equation is `a - 5 = -2`. Treat the equation like this: `a + (-5) = -2`. They are still the same. Again, it's one of those things that are unspoken but still there, there is an addition sign there. If it was `a - (-5) = -2` as you stated, then it would simplify into `a + 5 = -2` which in turn means that `a = -7`. That was the time when my teacher taught me that the operator goes with the number or term after it. So logically, if you reordered -5 to be in front of a, you would get `-5 + a = -2` which still gives the same answer.

• when your answering questions for khan academy, how do you answer 10 in a row when there's
only 8 questions?
• You can go to the video section of Khan Academy and do the same skill twice equaling ten questions correct and earn the badge.
• In , would it be correct to take a number, bring it to the other side of the equation, and change the operation to its inverse, or is doing the same thing on both sides the only correct way?
• I am not sure what you mean without an example. For x + 7 = 10, do you mean take the expression x+7 (not number) to the other side of the equation and change the operation from addition to its inverse which is subtraction?
If so, Yes. Then the equation becomes 0 = 10 -(x+7). Or 0 = 10 -x -7 or 0 = 3 - x. To solve for x, you still need to add x to each side, so x = 3.
It is much easier to solve x + 7 = 10 by subtracting 7 from both sides, x = 3. Same answer.