А) 17/20 - х = 14/20 - 3/20
17/20 - х = 11/20
х = 17/20 - 11/20
х = 6/20
х = 3/10
Проверка: 17/20 - 6/20 = 14/20 - 3/20
11/20 = 11/20
б) 8/15 - 7/15 + у = 14/15
1/15 + у = 14/15
у = 14/15 - 1/15
у = 13/15
Проверка: 8/15 - 7/15 + 13/15 = 14/15
14/15 = 14/15