10) 14/18 = 2X7/2X9 = 7/9
20/30 = 10X2/10X3 = 2/3
25/10 = 5X5/5X2 = 5/2
15/12 = 3X5/3X4 = 5/4
(Pour simplifier une fraction, il suffit de trouver un multiple commun au numérateur et au dénominateur)
11) a) 3/5 = 3X7/5X7 = 21/35
b) 3/4 = 3X15/4X15 = 45/60
c) 80/100 = 80:20/100:20 = 4/5
d) 49/21 = 49:7/21:7 = 7/3
12) a) 4/3 = 12/15 (car 4X3=12)
b) 5/6 = 30/36 (car 5X6=36)
c) 3,4/7,8 = 34/78 (car 7,8X10=78)
d) 56/24 = 7/3 (car 8X3=24)
e) 72/45 = 8/5 (car 8X9=72)
