Bonjour,

A= 7/3 - 15/12

= 7/3 - 5/3

= 2/3

C = 4/3 -7/3 ( 2/2-3/2)

= 4/3 -7/3 ( -1/2)

=4/3 +7/6

= 8/6 - 7/6

=1/6

B= (9/12 - 20/12) / -7/12

=-11/12  * -12/7

= 11/7

D= 9/64 -1/8

= 9/64 - 8/64

= 1/64

E=

3/5 -1/4 = 12/20 - 5/20 = 7/20

1+2/5 = 5/5 +2/5 = 7/5

(7/20) / (7/5)  

=7/20 * 5/7 = 35/ 140

= 7/  28

= 1/4