Question

I don’t know how to do this

Answer 1

What the problem is trying to show you, is that a positive number undoes a negative number and a negative number undoes a positive number meaning it changes it's value.

If I get 4 (positive number) and subtract it by 4 the answer will be 0 - the negative number -4 undid the number 4.

If I get -4 (negative number) and add 4 (positive number) the answer will be 0 - meaning the positive number 4 undid the number -4.

Hope it helped,

BioTeacher101

Answer 2

x + 4 = 10

the goal is to isolate the variable (x).  you do this by doing the opposite to all of the numbers that are on the same side as the variable (x).

If you subtract 4 from the left side, you must also subtract 4 from the right side to keep the equation balanced.

x + 4   -4   = 10    -4            (-4 was added to both sides because +4 and -4 = 0)

x  + 0        = 10 - 4

x               = 6

Another example:

x - 7 = 13

x - 7     +7     = 13    + 7

x + 0            = 20

x                  = 20

Hope this helps you to understand!