Calculer et donner le rusultat sous forme d'une fraction irréductible. Merci d'avance

Bonjour

Calculer et donner le résultat sous forme d'une fraction irréductible.

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

A = 1/4 - 5/12

A = (1 x 3) / (4 x 3) - 5/12

A = 3/12 - 5/12

A = - 2/12

A = (2x - 1) / (2 x 6)

A = - 1/6.

B = (1/3 - 3/4) : (1/4 - 4/3)

B = [(1 x 4) / (3 x 4) - (3 x 3) / (4 x 3)] : [(1x 3) / (4 x 3) - (4 x 4) / (3 x 4)]

B = (4/12 - 9/12) : (3/12 - 16/12)

B = - 5/12 : - 13/12

B = - 5/12 x - 12/13

B = 60/156

B = (12 x 5) / (12 x 13)

B = 5/13.

C = (3/4 - 5/8) - [7/6 - (- 3/2 - 2)]

C = [(3 x 2) / (4 x 2) - 5/8] - [7/6 - [- 3/2 - (2 x 2) / (1 x 2)]]

C = (6/8 - 8/8) - (7/6 - (- 3/2 - 4/2)]

C = - 2/8 - (7/6 - (- 7/2)]

C = - 2/8 - [7/6 + (7 x 3) / (2 x 3)]

C = - 2/8 - (7/6 + 21/6)

C = - 2/8 - 28/6

C = (- 2 x 3) / (8 x 3) - (28 x 4) / (6 x 4)

C = - 6/24 - 112/24

C = - 118/24

C = (2 x - 59) / (2 x 12)

C = - 59/12.