bonsoir

a)  4 ( 2 - x) + 5 = - 3 ( 2 x + 3) - 12

    8 - 4 x + 5 = - 6 x - 9 - 12

     - 4 x + 6 x = - 21 - 8 - 5

     2 x = - 34

     x = - 17

b) ( 3 x + 1 )/4 = ( 5 x - 2) / 5

    15 x + 5 = 20 x - 8

     15 x - 20 x = - 8 - 5

      - 5 x = - 13

         x = 13/8

c) x /3 + 5/6 = 1/2 - x

  2 x /6 + 5/6 = 3/6 - 6 x / 6

  2 x + 6 x = 3 - 5

   8 x = - 2

    x = - 1/4

d)  x - ( x + 1) = ( x + 3) - ( x -  3)

     x - x - 1 = x + 3 - x + 3

     x - x - x + x = 3 + 3 + 1

     0 x = 7 donc pas de solution

a) - 2 x + 7 = - x + 9

  - 2 x + x = 9 - 7

   - x = 2

     x = - 2

c) - 7 x - 12 = 8 x + 3

   - 7 x - 8 x = 3 + 12

   - 15 x = 15

     x = - 1