I've been looking for help on setting up this part of my homework so that I could finish it. If anyone can help, please do.

Part 1: Many people know that the weight of an object varies on different planets, but did you know that the weight of an object on Earth also varies according to the elevation of the object? In particular, the weight of an object follows this equation: , where C is a constant, and r is the distance that the object is from the center of Earth. (note: may need to convert... 1 mile= 5,280 feet.)

Solve the equation w= Cr^-2 for r.

I GOT: r=sqrt(C/w)

Is that right? If so, I need help moving forward.....

Part 1a: Suppose that an object is 100 pounds when it is at sea level. Find the value of C that makes the equation true. (Sea level is 3,963 miles from the center of the Earth.)

If I got C=1570536900 how can I plug it into part b?

Part 1b:Use the value of C you found in the previous question to determine how much the object would weigh in Death Valley (282 feet below sea level).

yes, on the first.

1a. c=wr^2 = 100*3,963^2

1b. w=c*/r^2=100*3963^2 / (3963-282)^2