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Lesson 3: One-step addition & subtraction equations

# One-step addition & subtraction equations

In this lesson, we learn how to solve simple equations with one unknown variable. To find the unknown, we remove extra numbers by doing the opposite operation on both sides of the equation. This keeps the equation balanced and helps us find the value of the unknown variable. 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 is queen elizabeth teaching me math
• she is the smartest
• May the queen rest in peace.
Rest In Peace Queen Elizabeth the second.😇
Also how could they be paying respects to the Queen if this was made ten years ago way before she died. Yes, I looked on youtube and it said ten years ago.
• it was her birthday when he uploaded it to YouTube all those years ago.
• What is the Queen Elizabeth picture for?
• Its cause she died 2 weeks ago
• 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.

• God save the Queen
• british people
• Why is Queen Elizabeth in the background for the whole video