6. how do u find the answer? i know the answer ( it's 208) but how u get it

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?

Write an expression that shows 3 more than 5 times a number

Astereo system is marked down from 450 to 382.50 what is the discount rate