Bonjour pouvez vous m’aidez svp je commence le chapitre et je ne comprend rien

Bonjour

A = - 2/3 + - 4/3 = - 2/3 - 4/3 = - 6/3 = (3 x -2) / (3 x 1) = - 2

B = - 7/5 x 5/9 = - 35/45 = (5 x - 7) / (5 x 9) = - 7/9

C = 11/12 + - 5/3 = 11/12 - (5 x 4) / (3 x 4) = 11/12 - 20/12 = - 9/12 = (3 x - 3) / (3 x 4) = - 3/4

D = 2/3 + 3/8 = (2 x 8) / (3 x 8) + (3 x 3) / (8 x 3) = 16/24 + 9/24 = 25/24

E = - 7 : - 21/10 = - 7 x - 10/21 = 70/21 = (7 x 10) / (7 x 3) = 10/3

F = 6/5 - 8/3 = (6 x 3) / (5 x 3) - (8 x 5) / (3 x 5) = 18/18 - 40/15 = - 22/15

G = - 3 + 7/4 = (- 3 x 4) / (1 x 4) + 7/4 = - 12/4 + 7/4 = - 5/4

H = - 2/- 5 x - 8/- 7 = 16/35

I = - 1/8 + 7/12 = (- 1 x 3) / (8 x 3) + (7 x 2) / (12 x 2) = - 3/24 + 14/24 = 11/24

J = 12/- 55 x 11/- 4 x 5 = 132/220 x 5 = 660/220 = (220 x 3) / (220 x 1) = 3.