Answer:
x = 3
Explanation:
To simplify this equation, don't worry about the -3, since there is one on both sides. Therefore, they cancel out.
So, 9 + x = 4x
When you plug 3 in for x, it becomes:
9 + 3 = 4 x 3
12 = 12
This equation is true, therefore, x is your answer!