In order to get the answer you will have to divide 30 by 100 then divide the number you get from that by 20 to receive your answer.
20/x=100/30
(20/x)*x=(100/30)*x
20=3.33333333333*x
(3.33333333333) to get x
20/3.33333333333=6
=6
Therefore your answer is "6."
Hope this helps