pourriez vous m aidez s il vous plait ????

A = 7/5 - 7/3 x 15/14
A = 7/5 - 105/42
A = 7 x 42 / 5 x 42 - 105 x 5 / 42 x 5
A = 294/210 - 525/210
A = - 231/210
A = 21 x - 11 / 21 x 10
A = - 11/10

B = 8/5 - 3/4 : 9/8
B = 8/5 - 3/4 x 8/9
B = 8/5 - 24/36
B = 8 x 36 / 5 x 36 - 24 x 5 / 36 x 5
B = 288/180 - 120/180
B = 168/180
B = 12 x 14 / 12 x 15
B = 14/15

C = 8/3 - 2/5
          7/5
C = 8 x 5 / 3 x 5 - 2 x 3 / 5 x 3
                   7/5
C = 40/15 - 6/15
             7/5
C = 34/15 : 7/5
C = 34/15 x 5/7
C = 170/105
C = 5 x 34 / 5 x 21
C = 34/21