Bonjour,
A = - 5/10 x 3/10
A = - 15/300
A = (15 x - 1) / (15 x 20)
A = - 1/20
B = 25/14 x 7/15
B = 175/210
B = (35 x 5) / (35 x 6)
B = 5/6
C = 14/30 x 18
C = 252/30
C = (6 x 42) / (6 x 5)
C = 42/5
D = 36/42 x 28/45
D = 1 008/1 890
D = (126 x 8) / (126 x 15)
D = 8/15.