The object is to get x by itself because "x" is the unknown
x + (x-8) = 12
Add your like values. This means add your x'es x = x
2x - 8 =12
Then add 8 to both sides of the equal sign, so you will get 2x =20
x =10
To check your answer, plug in your answer for 'x".
Both sides should equal the same. (10 = 10)...That's when you know that you've got the right answer.
Brian G.