Bonjour j'ai un DM pour demain pouvez-vous m'aider merci

bonjour

a = 17/18 - 7/9
a = 17/18 - 14/18
a = 3/18 ou 1/6

b = 3 + 1/2
b = 6/2 + 1/2
b = 7/2

c = 21/45 x 9/14
c = 189/630
c = 3/10

d = 22/5 - ( 5/3 + 11/15)
d = 22/5 - ( 25/15 + 11/15)
d = 22/5 - 36/15
d = 66/15 - 36/15
d = 30/15 = 2

e = 25/4 x ( 8/15 - 5/5)
e = 25/4 x ( 8/15 - 15/15)
e = 25/4 x - 7/15
e = - 175/60
e = 35/12

f est illisible