bonjour
3 - 5 : 6 /5
= 3 - 5 x 5/6
= 3 - 25 /6
= 18/6 - 25 /6
= - 7 /6
2 x ( 2 /15 - 2 /20 )
= 2 x ( 8/60 - 6 /60)
= 2 x 2 /60
= 4 /60
= 1 /15
