Bonjour
A = (- 7/15 + 5/12) x 20/- 9
A = [(- 7 x 4) / (15 x 4) + (5 x 5) / (12 x 5)] x - 20/9
A = (- 28/60 + 25/60) x - 20/9
A = - 3/60 x - 20/9
A = 60/540
A = (60 x 1) / (60 x 9)
A = 1/9
B = 25/4 - 3/4 x 8/9 + 2/6
B = 25/4 - 24/36 + 2/6
B = (25 x 9) / (4 x 9) - 24/36 + (2 x 6) / (6 x 6)
B = 225/36 - 24/36 + 12/36
B = 213/36
B = (3 x 71) / (3 x 12)
B = 71/12.
