Le 68svp je comprend pa du 4ème

bonjour

A = 9/5 + 22/20
A = 36/20 + 22/20
A =58/20 = 29/10

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

C = 8/3 - 5/7 x 21/20
C = 8/3 - 105/140
C = 8/3 - 21/28
C = 224/84 - 63/84
C = 161/84 = 23/ 12

Un petit effort, tu fais le dernier