Pouvez vous m'aidez svp​

Bonsoir,

A = 5/7 + 7/5

A = (5 x 5) / (7 x 5) + (7 x 7) / (5 x 7)

A = 25/35 + 49/35

A = 74/35

B = 3/8 : 9/2

B = 3/8 x 2/9

B = 6/72

B = (6 x 1) / (6 x 12)

B = 1/2

C = - 2 x - 5/7 - 1

C = 10/7 - (1 x 7) / (1 x 7)

C = 10/7 + 7/7

C = 3/7.