1) 3х-15=х+3
3х - х = 3 + 15
2х = 18
х = 9
2) 7-3х=х+11
4х = -4
х = - 1
3) 2(х+3)=х+13
2х + 6 = х + 13
2х - х = 13 - 6
х = 7
4) 4*(5-х)=3х-1
20 - 4х = 3х - 1
7х=21
х = 3
5) 3*(х-2)=х+4
3х -6 = х + 4
3х - х = 4 + 6
2х = 10
х = 5
6) 5(х-1)=4х+3
5х - 5 = 4х + 3
5х - 4х = 3 + 5
х = 8