а) \(\frac{5}{9}\) от числа 45: 45 : 9 ⋅ 5 = 5 ⋅ 5 = 25
б) \(\frac{3}{8}\) от числа 96: 96 : 8 ⋅ 3 = 12 ⋅ 3 = 36
в) число, \(\frac{2}{3}\) которого равны 42: 42 : 2 ⋅ 3 = 21 ⋅ 3 = 63
г) число, \(\frac{4}{7}\) которого равны 84: 84 : 4 ⋅ 7 = 21 ⋅ 7 = 147