Wesley has 480 stamps in his collection. He puts these stamps into display cases. Each display case contains 15 stamps. How many display cases does Wesley need for his stamp collection?

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?