The correct answer to this equation would be -9.
In order to solve this equation, you need to isolate the variable x. This means to get the variable by itself. So in order to do that, you subtract 10 on both sides of the equation. After doing that, your equation should like this: 4x=-36. We are still not done so we do the inverse of multiplication, which is division. We divide 4 on both sides of the equation and your answer should be -9.
Hope this helps!