1)9(x-1) = x+15

9x-9=x+15

8x=24

x=3

2) (11x + 14) - ( 5x-8) = 25

11x+14-5x+8=25

6x = 3

x= 0,5

3) 12-4 (x-3) = 39-9x

12-4x + 12 = 39-9x

5x+24 = 39

5x =15

x= 3

4) 2(3x+5) - 3(4x-1) = 11,8

6x +10 - 12x + 3 = 11,8

-6x+13= 11,8

-6x =12

x= 0,2