Ben has a coupon for an additional 15% off the sale price of any item in a store. He uses his coupon to buy a shirt whose sale price is already 20% off the original price. He pays $14.96, and there is no sales tax. What is the original price of the shirt?

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?