15 is 30% of what number?
( explain and/or show work)

Alright so I thought of it like this. 30 is 30% of 100
divide 30 in 1/2 you get 15. divide 100 in half to make it proportional. And you get 50.
But another more mathematical way is as follows
So you have your 15
Then you convert your percent into a decimal. 30% converts to 0.30
Divide your 15 by the converted percentage...so ex: 15/0.3
calculate and it should equal 50.
So 15 is 30% of 50

Is there a picture of a graph or whatever that goes along with this?