Пошаговое объяснение:

1)

(5x - 11)/7 = 32/56

56 * (5х - 11) = 32 * 7

280х - 616 = 224

280х = 224 + 616

280х = 840

х = 840 : 280

х = 3

2)

(7х - 9)/12 = 35/84

84 * (7х - 9) = 35 * 12

588х - 756 = 420

588х = 420 + 756

588х = 1176

х = 1176 : 588

х = 2

3)

(2х + 7)/17 = 60/68

68 * (2х + 7) = 60 * 17

136х + 476 = 1020

136х = 1020 - 476

136х = 544

х = 544 : 136

х = 4