Answer :
9/20 / 4/15 cross-reduce
3/5 / 1/5 reciprocal of 1/5
3/5 / 5/1 multiply straight-across
15/5 simplify
3
3/5 / 1/5 reciprocal of 1/5
3/5 / 5/1 multiply straight-across
15/5 simplify
3