Réponses

2012-11-07T10:40:14+01:00

21/28  +2/5 = 3/4 + 2/5 = (15+8)/20 = 23/20
15/25- 6/15= 3/5 - 6/15 = 9/15- 6/15 = 3/15 = 1/5
30/24+ 63/36 = 5/4 +3/2 = 5/4+6/4= 11/4
20/12+12/30= 5/3 + 2/5 = 25/15+6/15= 31/15