So first let's turn 15% into a decimal. For me personally, its less intimidating that way.
15%=0.15
now, let's say the number we are trying to find is x.
A trick I use for these questions is to look at the words. "<em>Of</em>" is used when something is multiplied. "<em>Is</em>" is used for equal signs. So if 20 is 0.15 of x, our formula is easy to figure out!
