Для начала упростим уравнения:

1) $x+5/12$ - 9/20 = 11/15
x + 5/12 - 9/20 = 11/15
x + 5/12 - 9/20 = 44/60
x + 10/60 - 27/60 = 44/60
x - 17/60 = 44/60
x = 44/60 + 17/60
x = 61/60

2) $x+4/25$ - 21/50 = 34/75
x + 4/25 - 21/50 = 34/75
x + 4/25 - 21/50 = 34/75
x + 6/50 - 21/50 = 34/75
x - 15/50 = 34/75
x = 15/50 + 34/75
x = 45/150 + 68/150
x = 113/150

Ответ: x = 61/60 и x = 113/150.