Combine like terms on the left side of the equation!
5x + 4x = 9x
13 + 2 = 15
Now, the equation looks like:
9x + 15 = 2x - 9
Begin to isolate x by performing the opposite operation by subtracting 15 on both sides of the equation
9x = -24
Isolate x by performing the opposite operation by dividing both sides of the equation by 9
