Bonjour
A = 3/8 x (1/3 + 7/9)
A = 3/8 x [(1 x 3) /(3 x 3) + 7/9]
A = 3/8 x (3/9 + 7/9)
A = 3/8 x 10/9
A = 30/72
A = (6 x 5) / (6 x 12)
A = 5/12
B = 49/18 : 14/9
B = 49/18 x 9/14
B = 441/252
B = (63 x 7) / (63 x 4)
B = 7/4
C = 15/2 - 25/2 : 5/3
C = 15/2 - 25/2 x 3/5
C = 15/2 - 75/10
C = 15/2 - (5 x 15) / (5 x 2)
C = 15/2 - 15/2
C = 0
D = 7/15 : (1/5 - 8/5)
D = 7/15 : (- 7/5)
D = 7/15 x (- 5/7)
D = - 35/105
D = (35 x - 1) / (35 x 3)
D = - 1/3.
