I am having trouble with question C.

(Window Boxes) Metal window boxes are manufactured in two process steps: stamping and assembly. Each window box is made up of three pieces: a base (one part A) and two sides (two parts B). The parts are fabricated by a single stamping machine that requires a setup time of 120 minutes whenever switching between the two part types. Once the machine is set up, the processing time for each part A is one minute while the processing time for each part B is only 30 seconds. Currently the stamping machine rotates its production between one batch of 360 for part A and one batch of 720 for part B. At assembly. parts are assembled manually to form the finished product. One base (part A) and two sides (part Bs). as well as a number of small purchased components, are required for each unit of final product. Each product requires 27 minutes of labor time to assemble. There are currently 12 workers in assembly. There is sufficient demand to sell every box the system can make.

a. What is the capacity of the stamping machine?

b What batch size would you recommend for the process?

c. Suppose they operate with the production cycle of 1,260 part As and 2,520 part Bs. What would be the average inventory of part A?