1) 3 - 5х = 0

-5х = -3

х = 0,6

2) 8х - 5 = х - 40

8х - х = -40

7х = -40 + 5

7х = -35

х = -5

3) 6х - (2 - 3х) = 16

6х - 2 + 3х = 16

9х - 2 = 16

9х = 16 + 2

9х = 18

х = 2

4) 5(х + 3) = 8(10-х)

5х + 15 = 80 - 8х

5х + 8х + 15 = 80

5х + 8х = 80 - 15

13х = 80 - 15

13х = 65

х = 5