Add 2 to the left side of an equation and subtract 5 from the right side. What number should he now subtract from the left side to make a true equatio?

Question

4th grade math problem equality. Need to make a true equation.

Answer 1

If you do something to one side of the equation you must do the same thing to the other side:

You add 2 to the left side, and subtract 5 from the right:

If you added 2 to the left side and subtracted 5 from the right, you first have to subtract the 2 you added, then you have to subtract the 5 you subtracted from the right side. 5 + 2 = 7 so you have to subtract 7 from the left to make the equation true.

Answer 2

Let's start out with a true equation. You can pick any true equation. I will pick 5=5

 

5=5

 

I add 2 to the left side of the equation

 

5+2=5

7=5

 

I subtract 5 from the right side of the equation above

 

7=5-5

7=0

 

Now I determine what I need to subtract from the left side of the above equation to make it equal 

 

7=0; to make this true, I must subtract 7 from the left side and that is the answer

7-7=0

0=0

 

ANSWER: I must subtract 7 from the left side to make it equal