помогите даю 60 баллов!​

1. a)= - 3/14

b) = -23/36

c) = -5/12

d) = -3/20

2.

= -1/4 × 1/5 + 2/3 × 9/10 = -1/20 + 3/5 = 11/20

3.

a) = -15/91 - 20/91 = -5/13    b) = 1/5 × 7/3 - 3/5 × (-1/18) = 7/15 + 1/5 × 1/6 = 7/15 + 1/30 = 1/2