1. 3/7 = 72/x
By cross multiplication we get :
➟ 3x = 72 × 7
➟ x = 72 × 7/3
➟ x = 24 × 7
➟ x = 168
2. m/8 = 8/20
➟ 20m = 8 × 8
➟ 20m = 64
➟ m = 64/20
➟ m = 16/5