how do i do these questions with work shown? thank you

(c) Using the current production batch size of 35 parts, how long would it take to produce a batch starting with an empty system (with no setup done)? Assume that all the units in the batch have to stay together (no smaller transfer batches allowed) when transferred to either Jill or Jen, who then processes the entire batch (the batch cannot be divided among the two workers). Also all the units have to stay together when transferred from either Jill or Jen to Julie. (a) Using the current production batch size of 35 parts, how long would it take to produce a batch starting with an empty system (with no setup done)? Assume that the units in the batch do not have to stay together; specifically, units are transferred to Jill or Jen, the moment they are done with task 2 and either Jill and Jen starts processing as early as possible. Assume that either Jill or Jen processes the entire batch (the batch cannot be divided among the two workers). Similarly, units are transferred to Julie as soon as they are done with task 3 and Julie processes them as early as possible. (C) (Challenging) Suppose the process manager's first objective is to guarantee that a batch can be ready in 5 hours or less. His second concern is flow rate. What batch size would you suggest, given the assumptions in (c)? given the assumptions in (d)