Summer brought 45 feet of wood trim at a home depot store. The wood cost 1.65 per foot, including sales tax. Of summer paid with a 100$ bill, how much change should she have received?

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?