In this problem you are trying to find what is 15% of 240.
Easy method:
Turning 15% into a decimal and then multiplying. To convert to a decimal move the decimal point two to the left and you'll get .15
.15 x 240 = 36
Other method:
You can also do cross multiplication by setting up two fractions

15 x 240 = 3,600
3,600/ 100 = 36
Answer is 36