An engineer wants to test the complex and dangerous process of filling and emptying a tank of liquid hydrogen. The tank has a volume of 400 cm3. The tank can be filled 50 cm3 per hour faster than it can be emptied.

Part A. Write an expression for the number of hours it takes to fill this tank, in terms of r

Part B. Wrote an expression for the number of hours it takes to empty this tank, in terms of r:

Part C. Wrote an equation for the total time in hours it takes to fill and empty this tank in terms of r. Simplify.

Part D. Find the rate that would allow you to fill and empty the tank in 100 hours. Check for extraneous solutions, and show your work. Round to the nearest tenth.