hirondelle52

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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