URGENT vraiment besoin d aide. merçi

A = 2/3 +4/5 = 2x5/3x5 + 4x3/3x5 = 10/15 + 12/15 = 22/15
B = 1/6-5/7 = 1x7/6x7 - 5x6/7x6 = 7/42-30/42 = -23/42
C = -3/2+7/9 = -3x9/2x9 + 7x2/9x2 = -27/18+14/18 = -13/18


A = 3/7 +5/2
A = 6/14+35/14
A = 41/14

B = -7/3+7/8
B = -7x8/8x3+7x3/8x3
B = -56/24+21/24
B = -35/24

C = -8/5-5/3
C = -8x3/5x3-5x5/3x5
C = -24/15 -25/15
C = -49/15

D = 1/9- -7/4
D =4/9x4 + 7x9/4x9
D = 4/36+63/36
D = 67/36