I tired some formulas but they were not helpful, I really need help on answering the following problem!

Williams Optical Inc. is considering a new lean product cell. The present manufacturing approach produces a product in four separate steps. The production batch sizes are 51 units. The process time for each step is as follows: Process Step 1 4 minutes Process Step 2 7 minutes Process Step 3 9 minutes Process Step 4 5 minutes The time required to move each batch between steps is 10 minutes. In addition, the time to move raw materials to Process Step 1 is also 10 minutes, and the time to move completed units from Process Step 4 to finished goods inventory is 10 minutes. The new lean layout will allow the company to reduce the batch sizes from 51 units to 3 units. The time required to move each batch between steps and the inventory locations will be reduced to 2 minutes. The processing time in each step will stay the same. Determine the value-added, non-value-added, and total lead times, and the value-added ratio under the present and proposed production approaches. If required, round percentages to one decimal place. Present Approach Proposed Approach Value-added time min min Non-value-added time min min Total lead time min min Value-added ratio (as a percent) %