Un peu d'aide pour le numéro 1 svp

bonsoir

a = 2/3 + 25/15
a = 10/15 + 15 /15 = 25/15 = 5/3

b = 3/28 + 35/28 = 38/28 = 19/14

c = 56/16 - 11/16 = 45/16

d = 10/20 + 5/20 + 1/20 = 16/20 = 4/5

e = 9/7 - ( 15/21 - 10/21)
e = 9/7 - 5/21 = 27/21 - 5/21 = 22/21