Ответ:

1) 6х+7=5х+3

6х-5х=3-7

х=-4

2) 15х-4(3х+5)=7(2х+5)

15х-12х-20=14х+35

3х-14х=35+20

-11х=55

х=-5

3) 5(3х-8)-3(2-5х)=4х-20

15х-40-6+15х=4х-20

30х-4х=46-20

26х=26

х=1

4) 2(х-23)+3(15-х)=х+1

2х-46+45-3х=х+1

-х-х=1+1

-2х=2

х=-1