Multiply both sides of the equation by 3.
Combine 3x and 2x to get 5x.
Subtract 5 from -15 to get -20.
Subtract 9x from both sides.
Combine 5x and -9x to get -4x.
Add 20 to both sides. Anything plus zero gives itself.
Divide both sides by -4.
Divide 20 by -4 to get -5.