If y varies directly as x, and y = 16 as x = 4, find y for the x-value of 2

Plot the points (0,6), (3,15.8), and (9.5,0) using the graphing tool, and find the function

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83

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?