Найдите значения выражения:

а) 5/4 : (3 3/8 - 1 1/2)

б) (5/15+1/12) * 30

А) 5/4 : (3 3/8 - 1 1/2) = 2/3

1) 3 3/8 - 1 1/2 = 3 3/8 - 1 4/8 = 2 11/8 - 1 4/8 = 1 7/8 = 15/8

2) 5/4 : 15/8 = 5/4 * 8/15 = (1*2) / (1*3) = 2/3

б) (5/15 + 1/12) * 30 = 12 1/2

1) 5/15 + 1/12 = 20/60 + 5/60 = 25/60 = 5/12

2) 5/12 * 30 = 150/12 = 12 целых 6/12 = 12 целых 1/2 = 12,5