Judi has 80 pieces of candy and wendy has x pieces of candy fewer than judi. how many pieces must judi give to wendy so that both will have an equal number? solve for terms of x

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?