Пошаговое объяснение:

№1

1) 1/11 - 1/33 = 3/33 - 1/33 = 2/33

2) 1 - 2/33 = 33/33 - 2/33 = 31/33

№2

1) 5/12 + 5/18 = 15/36 + 10/36 = 25/36

2) 6 - 25/36 = 5 36/36 - 25/36 = 5 11/36