Mark Andrews spends his days off working a children's clothing store. He is paid on a straight commission based on the amount of sales he is able to make. If he
gets 4% on sales of $5,000 or less and 5% on sales in excess of $5,000, what were
his total sales for a week in which he was paid $594.50?

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?