What is a real world situation using algebraic expression?

Answer 1

Let's say I owe my brother some money (m). As a gift to me, he takes off $2 (Woo Hoo...). Now I owe him $7. How much did I originally owe him?

Since debt is shown with negative numbers, my equation would look like this: m - (-2) = -7

I can change this equation to an addition problem without changing the outcome because subtracting a negative number is the same as adding a positive number.

m + 2 = -7

To solve this, I will need to get m alone on one side of the equal sign. I will do this by subtracting 2 on each side of the equal sign. Now the problem looks like this: m = -9 .

This answer makes sense because if I had originally owed by brother $9 and he took off $2, that means I would only owe him $7.