PLEASEE HELP. *EXTRA POINTS* DONT SKIP:((

Can you me find the slope! (30 points)

If you have 12 feet of string and you cut it into equal length of 5 inches each how much string will be left

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?