Calculer et donner le résultat sous la forme la plus simple possible.

A = 1/7 - 5/7
A = -4/7

B = 1/2 + 5/6
B = 1 x 3 / 2 x 3 + 5/6
B = 3/6 + 5/6
B = 8/6
B = 2 x 4 / 2 x 3
B = 4/3

C = 2/5 - 3/4
C = 2 x 4 / 5 x 4 - 3 x 5 /4 x 5
C = 8/20 - 15/20
C = -7/20

D = 3/4 x 7/11
D = 3 x 7 / 4 x 11
D = 21/44

E = -2/15 x 25/6
E = -2 x 25 / 15 x 6
E = -30/150
E = 30 x -1 / 30 x 5
E = -1/5

F = 4/7 : 5/3
F = 4/7 x 3/5
F = 4 x 3 / 7 x 5
F = 12/35