Réponse :
Bonjour,
Explications étape par étape :
Il faut les mettre sous forme irréductible ?
6/18 = (6*1)/(6*3) = 1/3
90/40 = (10*9)/(10*4) = 9/4
8/20 = (4*2)/(4*5) = 2/5
3/21 = (3*1)/(3*7) = 1/7
6/27 = (3*2)/(3*9) = 2/9
64/56 = (8*8)/(8*7) = 8/7
55/66 = (11*5)/(11*6) = 5/6
18/24 = (6*3)/(6*4) = 3/4
8/40 = (8*1)/(8*5) = 1/5
63/70 = (7*9)/(7*10) = 9/10
Voilà :), bonne journée