Вычислите 5/8-(1/3+1/6).16/21-(1/6+2/7).7/8-(1/4+2/5

1 пример
1. 1/3+1/6 = 2/6+1/6=3/6=1/2
2. 5/8 - 1/2 = 5/8 - 4/8 = 1/8

2 пример
1. 1/6+2/7 = 7/42+12/42 = 19/42
2. 16/21 - 19/42 = 32/42 - 19/42 = 13/42

3 пример
1. 1/4+2/5 =  5/20+8/20 = 13/20
2. 7/8 - 13/20 = 35/40 - 26/40 = 9/40