4х - 2х + 5х = 35
7х = 35
х = 35 : 7
х = 5
7х + 2х + 5х = 19 + 21
14х = 40
х = 40 : 14
х = 40/14 = 20/7
20 - ( 6х - 4х ) = 12
20 - 2х = 12
2х = 20 - 12
2х = 8
х = 8 : 2
х = 4
100 + 24 = 6х- 4х
124 = 2х
2х = 124
х = 124 : 2
х = 62
