bonsoir
3/4 + 1 /12 = 9/12 + 1/12 = 10 /12 = 5 /6
7/15 + 1 /3 = 7/15 + 5/15 = 12 /15 = 4 /5
3/10 - 5 /100 = 30/100 - 5 /100 = 25 /100 = 1 /4
17/6 - 1 /2 = 17/6 - 3 /6 = 14 /6 = 7 /3