Explications étape par étape:

a) 35/55 = (7×5)/(11×5) = 7/11

b) 72/135 = (8×9)/(15×9) = 8/15

c) 75/24 = (25×3)/(8×3) = 25/8

d) 99/22 = (9×11)/(2×11) = 9/2

e) 34/51 = (2×17)/(3×17) = 2/3