Bonjour,
1)
28/12 = 14/6 = 7/3
38/42 = 19/21
60/44 = 30/22 = 15/11
34/22 = 17/11
15/12 = 5/4
200/70 = 20/7
25/45 = 5/9
25/100 = 5/20 = 1/4
18/54 = 2/6 = 1/3
46/74 = 23/37
55/33 = 5/3
56/40 = 28/20 = 14/10 = 7/5
91/52 = 7/4
24/20 = 12/10 = 6/5
26/39 = 2/3
27/15 = 9/5
95/76 = 5/4