Réponse et explications :
25/35 = 5 x 5 / 5 x 7 = 5/7
64/16 = 4 x 16 / 1 x 16 = 4/1 (on écrit alors 4)
2800/300 = 100 x 28 / 100 x 3 = 28/3
90/66 = 6 x 15 / 6 x 11 = 15/11
100/175 = 25 x 4 / 25 x 7 = 4/7
34/51 = 17 x 2 / 17 x 3 = 2/3
