Réponses

2013-03-17T17:10:17+01:00

x + (x - 5) + (x + 2) = 39
3x - 5 + 2 = 39
3x-3 = 39
3x = +3+39 = 42
x = 14
Marie a x = 14 ans
Florent a (x-5) = 14-5 = 9
Chloe a (x+2) = 14+2 = 16

voila en esperant que tu aies compris.