Bonsoir,

A = 3/4 + 8/5

A = (3 x 5) / (4 x 5) + (8 x 4) / (5 x 4)

A = 15/20 + 32/20

A = 47/20

B = 3/4 - 9/7

B = (3 x 7) / (4 x 7) - (9 x 4) / (7 x 4)

B = 21/28 - 36/28

B = - 15/28

C = 7/3 x - 5/6

C = - 35/18

D = 21/- 25 x - 10/49

D = 210/1 225

D = (35 x 6) / (35 x 35)

D = 6/35.