Frans mower rental charges a flat rate of $12 per day for a mower rental +2 dollars per hour the mower is being used. if the number of hours is represented by each which algebraic expression represents the overall rate for each hours of mower rental

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?