Question

In these equations;

10+x=15 subtract 10 to both sides

and

x-32=20 add 32 to both sides


how do you know when you are supposed to add or subtract a number to both sides of an equation??

Answer 1

When dealing with these types of equations the main goal is to find x. In order to find x you must get x by itself.

In the example 10+x=15 you subtract 10 on both sides so that way x is by itself

10+x=15
x=15-10
x=5

In the other equation x-32=20 you have to add 32 to both ways in order to get x by itself

x-32=20
x=20+32
x=52

- you subtract the number from both sides when it is positive
- you add the number to both sides when it is negative
- when you +\- the same number with two different signs they will cancel out
ex:

-23+23=0
-5+5=0