Réponse:
1) 10 + 2x
2) 18 - 2x
3) 10 + 2x = 18 - 2x
x = 2
4) 5x
5) 18 - 3x
6) 5x = 18 - 3x
5x + 3x = 18
8x = 18
x = 18/ 8
x =9 /4
