5/9+3/4,23/40-3/8,9/35-3/28

Приводим к общему знаменателю, считаем, сокращаем:

5/9 + 3/4 = 20/36 + 27/36 = 47/36 = 1 11/36

23/40 - 3/8 = 23/40 - 15/40 = 8/40 = 1/5 = 0,2

9/35 - 3/28 = 36/140 - 21/140 = 15/140 = 3/28