I first subtracted 6x from both sides

6x + 7 = 8x - 13
-6x + 6x + 7 = 8x - 13 - 6x
7 = 2x - 13

I then added 13 to each side

7 = 2x - 13
13 + 7 = 2x - 13 + 13
20 = 2x

Finally I divided both sides by 2

²⁰ /₂ = ^2x /₂
10 = x

Penny