Bonsoir,
Numerateur : au dessus de la barre de fraction
Denominateur : en dessous de la barre de fraction
A) 15 = 1 x 15
1/3 = (1 x 15)/(3 x 15) = 15/45
B) 15 = 3 x 5
1/3 = (1 x 5)/(3 x 5) = 5/15
C) 18 = 9 x 2
9/7 = (9 x 2)/(7 x 2) = 18/14
D) 100 = 10 x 10
3/10 = (3 x 10)/(10 x 10) = 30/100
E) 6 = 18 ÷ 3
18/15 = (18 ÷ 3)/(15 ÷ 3) = 6/5
F) 4 = 32 ÷ 8
40/32 = (40 ÷ 8)/(32 ÷ 8) = 5/4