If one side of a square is represented by 18x − 20 and the adjacent side is represented by 42 − 13x, find the length of the side of the square.
16
Sides equal: 18x − 20 = 42 − 13x.18x + 13x = 42 + 20 ⇒ 31x = 62 ⇒ x = 2.Side = 18(2) − 20 = 16.