Réponses

2014-03-16T21:02:24+01:00
A= 2/5 + 1/4
A= 2x4 / 5x4 + 1x5 / 4x5
A= 8/20 + 5/20
A= 13/20

B= 2/5 - 1/4
B= 2x4 / 5x4 - 1x5 / 4x5
B= 8/20 - 5/20
B= 3/20

C= A/B
C= 13/20 / 3/20
C= 13/20 x 20/3
C= 13/3