bonjour

D = - 13/6 + 5/7

D = -  91/42 + 30/42

D =  - 61/42

E = 5/8 - 13/6

E =  15/24 -  52/24

E = -  37/24

F = 5/2 - 11/4

f =  10/4 - 11 /4

F = - 1 /4