Réponse :

coucou,

7x +17 = 9x+29

7x - 9x = 29 -17

-2x = 12

-x = 6

x = -6

Vérification:

7x + 17 = 9x +29

7*-6 + 17 = 9*-6 +29

-42 +17 = -54 + 29

-25 = -25

donc juste.