Bonjour,
Exercice 47
a= 9/12 + 11/12 = 20/12 = 10/6 = 5/3
b= 9/12 - 11/2 =2/12 = 1/6
c= 7/18 - 15/18 = -8/18 = -4/9
Exercice 53
a)
1/5 + 2/3 = 3/15 + 10/15 = 13/15
b)
15/15 - 13/15 =2/15
