1)3х+15 = 7 -5х
3х + 5х = -15 +7
8х = -8
х = -1
2)4х - 36 = 3х - 24
4х - 3х = 36-24
х = 12
3)21 - 14х = 15 - 15х
-14х + 15х = -21 + 15
х = -6
4)13 - 2х +5 = х-3
-2х - х = -13 - 5 -3
-3х = -21
3х = 21
х = 7
5)26 - 17 + 2х = 5х
2х - 5х = -26+17
-3х = -6
3х = 6
х = 2
6)19 - 6х - 16 = 2х - 37
-6х - 2х = -19 +16 - 37
-8х = -40
8х = 40
х = 5
7)23 - 12х -32 = 1-17х
-12х +17х = -23 +32 +1
5х = 10
х = 2