Bonjour
9/21 = ( 9 : 3 ) / ( 21 : 3 ) = 3 /7
16/20 = ( 16 : 4 ) / ( 20 : 4 ) = 4 /5
85/90 = ( 85 : 5 ) / ( 90 : 5 ) = 17/18
30/10 = ( 30 / 10 ) / ( 10 : 10 ) = 3 /1 = 3
