Answer :
To get the equivalent you have to half the denominator and the numerator so therefore it is 1/5 as you divide it by 2.
1/5, 2/10, 3/15, 4/20, 5/25, 6/30, 7/35, 8/40, 9/45, 10/50, 11/55, 12/60, 13/65, 14/70, 15/75, 16/80, 17/85, 18/90, 19/95, 20/100