Filipe paid $250 for 5 video games that were all the same price he used a deal that took $ 15 off his entire purchase. What was the original cost of each game ?

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?