Réponses

2014-01-24T17:07:08+01:00
Bonjour

A=2a-(5a+b) = 2a -5a -b = -3a -b
b=15-(3-2a)+(3a-7) = 15 -3 +2a + 3a -7 = 5a +5
C  4+(-3a+2a)-(5-2a) = 4 - 3a + 2a - 5 +2a = a -1