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