Question

2x + 8 = 15 i do not know what to do

Answer 1

I could not say that any better!

Answer 2

Okay here is step by step.

2x + 8 = 15

2x = 15 - 8

2x = 7

7/2 = 3.5

3.5 = x

Because we use the laws of substitution switching the numbers to the other side, which is allowed because they still mean the same thing.

Hope this helps.