vous pouvez m'aider pour l'exercice 23 svp

bonjour

a = 9/42 + 10/42 = 19/42

b = 2/3 - 63/42
b = 28/42 - 63/42 =  - 35/42

c = 4/9 - 2 x 15/ 12
c = 4/9 - 30/12
c = 16/36 - 90/36 = - 80/36 = - 20/9

d = 18 - 16 : 4/7
d = 18 - 16 x 7/4
d = 18 - 112/4
d = 72/4 - 112/4
d =  - 40/4 = - 10

e = 2³ / 3 ² : 2⁴/3
e = 8/9 : 16/3
e = 8/9 x 3/16
e = 24/144 = 1/6