3x + 7 = x - 15 First, make sure to subtract from both sides. Second, simplify 3x - x to get 2x, and then keep the 7. Third, subtract from both sides. Fourth, simplify -15 - 7 to get -22. Fifth, take the 2 and divide both sides by it, keeping the by itself. Sixth, since 11 goes into 2 to get 22, simplify the fraction to 11.