Bonjour Pouvez vous m'aider pour l'exercice 9et 10 je n'es pas comprit mrc

Bonjour,

9)

A = 3/4 + 5/8 x 3/10

A = 3/4 + 15/80

A = (3 x 4) / (4 x 4) + (5 x 3) / (5 x 16)

A = 12/16 + 3/16

A = 15/16

B = 2/5 : (3 - 7/10)

B = 2/5 : [(3 x 10) / (1 x 10) - 7/10]

B = 2/5 : (30/10 - 7/10)

B = 2/5 : 23/10

B = 2/5 x 10/23

B = 20/115

B = (5 x 4) / (5 x 23)

B = 4/23

10)

A = 2 - 3/4 x 8/21

A = 2 - 24/84

A = (2 x 7) / (1 x 7) - (12 x 2) / (12 x 7)

A = 14/7 - 2/7

A = 12/7

B = (3/4 - 5/3) : - 7/12

B = [(3 x 3) / (4 x 3) - (5 x 4) / (3 x 4)] : - 7/12

B = (9/12 - 20/12) : - 7/12

B = - 11/12 x - 12/7

B = 132/84

B = (12 x 11) / (12 x 7)

B = 11/7.