Réponse :
A= 2/5 x 3/4 B= 5/3 x 7/2 x 3/7 x 9/5
=2x3/5x3 = 5x7x3x9 / 3x2x7x5
= 6/15 = 945/ 210
= 189/42
C=20/9 x 18/50. D=15/49 x 21/10
= 20x18 / 9x50. = 15x21 / 49x10
= 360/450. = 315/490
= 72/90. = 63/98
= 9/45
E= 3x5/3. F= 240x 35 : 100
= 15/3. = 8400 : 100
= 5. = 84
