Bonjour
A = 9/5 - - 3/5 x 7/4
A = (9 x 4) / (5 x 4) + 21/20
A = 36/20 + 21/20
A = 57/20.
B = 9 / (5 + 5/- 7)
B = 9 : [(5 x 7) / (1 x 7) - 5/7]
B = 9 : (35/7 - 5/7)
B = 9 : 30/7
B = 9 x 7/30
B = 63/30
B = (3 x 21) / (3 x 10)
B = 21/10
C = (- 4/5 - - 14/15) : (9/5 + 3/5 x 7/-2)
C = [(- 4 x 3) / (5 x 3) + 14/15] : [(9 x 2) / (5 x 2) - 21/10]
C = (- 12/15 + 14/15) : (18/10 - 21/10)
C = 2/15 : - 3/10
C = 2/15 x - 10/3
C = - 20/45
C = (5 x - 4) / (5 x 9)
C = - 4/9.
