Problem 1

4x+8=12

Problem 2

2x+7=15

The answer to the first problem is x=1

The answer to the 2nd problem is x=4

In the first problem, you need to subtract the 8 from both sides of the equation then divide 4 by both sides which makes 4 cancel itself out leaving x and 12 leaving 1.

X=1 ...

x=4 ...