S'il vous plaît quelqu'un peut m'aider sur cet exercice ​

Bonjour,

A = 9 + - 1/10 x 7/5

A = 9 - 7/50

A = (9 x 50) / (1 x 50) - 7/50

A = 450/50 - 7/50

A = 443/50

B = 9 - 9/10 x 80/27

B = 9 - 720/70

B = (9 x 70) / (1 x 70) - 720/70

B = 630/70 - 720/70

B = - 90/70

B = (10 x - 9) / (10 x 7)

B = - 9/7

C = - 32/7 - 8/21 x 49/24

C = - 32/7 - 392/504

C = - 32/7 - (56 x 7) / (56 x 9)

C = - 32/7 - 7/9

C = (- 32 x 9) / (7 x 9) - (7 x 7) / (9 x 7)

C = - 288/63 - 49/63

C = - 239/63

D = 7/8 : (- 7/9 - - 11/8)

D = 7/8 : [(- 7 x 8) / (9 x 8) + (11 x 9) / (8 x 9)]

D = 7/8 : (- 56/72 + 99/72)

D = 7/8 : 43/72

D = 7/8 x 72/43

D = 504/344

D = (8 x 63) / (8 x 43)

D = 63/43.