I need hel right awayyy please Nikos finds a toy train set on sale for 20% off at a toy store. The original
price was $35. What is the sale price Nikos must pay for the train set?

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?