Bonjour,
a)
(2*2*2*2*3)/(3*5*5) = 16/25
b)
(2*3*3*7)/(2*2*3*3*5*7) = 1/10
c)
(2*2*2*3*3*5)/(2*2*3*3*7) =10/7
d)
(2*2*5*11)/(2*2*5*5) =11/5