Ответ:

Пошаговое объяснение:

1)

х + 4/21 = 16/35 + 4/15

х + 20/105 = 48/105 + 28/105

х + 20/105 = 76/105

х = 76/105 - 20/105

х = 56/105

х = 8/15

2)

х - 8/19 = 2/3 + 4/57

х - 24/57 = 38/57 + 4/57

х - 24/57 = 42/57

х = 42/57 + 24/57

х = 66/57

х = 1 9/57

х = 1 3/19

3)

х - 8/9 = 19/36 - 3/8

х - 64/72 = 38/72 - 27/72

х - 64/72 = 11/72

х = 11/72 + 64/72

х = 75/72

х = 1 3/72

х = 1 1/24