Carol buys last year's best-selling novel, in hardcover, for $24.65. this is with a 15% discount from the original price. what was the original price of the novel? for your !

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?