Quelqu’un peut m’aider svp?

Bonjour

A = - 7/5 x 1/2 - 3/10 x 3/4

A = - 7/10 - 9/40

A = (- 7 x 4) / (10 x 4) - 9/40

A = - 28/40 - 9/40

A = - 37/40

B = (3/2 - 5/4) x 2/3 - (7/6 - 1)

B = [(3 x 2) / (2 x 2) - 5/4] x 2/3 - [7/6 - (1 x 6) / (1 x 6)]

B = (6/4 - 5/4) x 2/3 - (7/6 - 6/6)

B = 1/4 x 2/3 - 1/6

B = 2/12 - 1/6

B = 2/12 - (1 x 2) / (6 x 2)

B = 2/12 - 2/12

B = 0

C = (9/4 - 1/2) : 3/2 + 1/3 (7/2 - 2)

C = [9/4 - (1 x 2) / (2 x 2)] : 3/2 + 1/3 [7/2 - (2 x 2) / (1 x 2)]

C = (9/4 - 2/4) : 3/2 + 1/3 (7/2 - 4/2)

C = 7/4 : 3/2 + 1/3 x 3/2

C = 7/4 x 2/3 + 3/6

C = 14/12 + (3 x 2) / (6 x 2)

C = 14/12 + 6/12

C = 20/12

C = (4 x 5) / (4 x 3)

C = 5/3.