4× х =42 + 42 х ÷ 5 =40-20
4х = 42 + 42 4х = 84 х = 21 ------------------------- 42х : 5 = 40 - 20 42х : 5 = 20 42х = 20 * 5 42х = 100 х = 2целых 16/42 = 2целых 8/21