Lydia made 56,750 last year. She paid 1200 in student loan interest and made a 3000 contribution to her IRA. On her federal tax return she will claim 52550 to be her

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?