qui peux m.aider pour le 68 merci

Bonjour,

A = 9/5 + 2/5 x 11/4
A = 9/5 + 22/20
A = 9 x 4 / 5 x 4 + 22/20
A = 36/20 + 22/20
A = 56/20
A = 4 x 14 / 4 x 5
A = 14/5

B = 8/3 - 8/3 x 9/16
B = 8/3 - 72/48
B = 8 x 16 / 3 x 16 - 72/48
B = 128/48 - 72/48
B = 56/48
B = 8 x 7 / 8 x 6
B = 7/6

C = 8/3 - 5/7 : 20/21
C = 8/3 - 5/7 x 20/21
C = 8/3 - 100/147
C = 8 x 49 / 3 x 49 - 100/147
C = 392/147 - 100/147
C = 292/147

D = 1/7 + 6/5 : 12/35
D = 1/7 + 6/5 x 35/12
D = 1/7 + 210/60
D = 1 x 60 / 7 x 60 + 210 x 7 / 60 x 7
D = 60/420 + 1470/420
D = 1530/420
D = 30 x 51 / 30 x 14
D = 51/14