Need help finding out something, refer to picture

The circle below is centered at the point (3, 1) and has a radius of length 2. what is the equation?

What is the surface area of a cube with the volume of 729 ft?

Which problem would you use the following proportion to solve for? 24/x=40/100 a. what is 40% of 24? b. what percent is 24 of 40? c. twenty-four is 40% of what number? d. forty percent of 24 is what number?