Svp aider moi c'est urgent

A = - 1/5 x - 25/- 20 x 12/ - 9
A = - 1/5 x 25/20 x - 12/9
A = - 25/100 x - 12/9
A = 300/900
A = 300 x 1 / 300 x 3
A = 1/3

B = - 1/3 + 4/3 x (5/3 : 5/2)
B = - 1/3 + 4/3 x (5/3 x 2/5)
B = - 1/3 + 4/3 x 10/15
B = - 1/3 + 40/45
B = - 1 x 15 / 3 x 15 + 40/45
B = - 15/45 + 40/45
B = 25/45
B = 5 x 5 / 5 x 9
B = 5/9

C = - 4 + 3 x 2 - 5 - 1 x (3 + 1)
C = - 4 + 6 - 5 - 1 x 4
C = - 4 + 6 - 5 - 4
C = - 4 - 5 - 4 + 6
C  = - 13 + 6
C = - 7