okay so here goes the third answer after two brilliant answers!
so we shall do this like!
we will place 100 below 15 and multiply it by 200 which means that 15% of 100% (or whole) of 200 , so lets do it!
15/100 * 200 (now lets reduce them, so for that we will sut the two zeroes of 200 and 100 )
=15 * 2 ( so now we shall simply multiply this)
= 30 ANSWER
i hope u have understood by now but if not then pls be free to ask!
hope this helps!