x = measure of each of the legs
"perimeter is 8 more than 2 times one of the legs" ---> P = 2x+8
P = 28 is the given perimeter
So,
P = 2x+8
28 = 2x+8
2x+8 = 28
2x = 20
x = 10
If x = 10, then the two legs add up to x+x = 10+10 = 20
Leaving P-20 = 28-20 = 8 inches left over for the base
You have the correct answer (choice D, 8 inches) though your steps are a bit confusing at some parts. Such as the part where you wrote 2x = 10 twice. I think I know what you were trying to say.
