Bonjour,
L = 1/5 - 3/5 x 1/6 + 1/2
L = 1/5 - 3/30 + 1/2
L = (1 x 6) / (5 x 6) - 3/30 + (1 x 15) / (2 x 15)
L = 6/30 - 3/30 + 15/30
L = 18/30
L = (6 x 3) / (6 x 5)
L = 3/5
M = (1/5 - 3/10) - (1/6 - 1/2)
M = [(1 x 6) / (5 x 6) - (3 x 3) / (10 x 3)] - [(1 x 5) / (6 x 5) - (1 x 15) / (2 x 15)]
M = (6/30 - 9/30) - (5/30 - 15/30)
M = - 3/30 - (- 10/30)
M = - 3/30 + 10/30
M = 7/30.