Réponses

2013-10-21T15:27:52+02:00
A = 4/21-(-9/7)=4/21-(-27/21)=4/21+27/21=31/21
B = 5/6-(-1/7)=35/42-(-6/42)=35/42+6/42=41/42
C = -7/6+4/9=-21/18+8/18=-13/18