Please walk through this STEP BY STEP. I have no idea where to even start.

4.15. Given the following product tree, explode, offset, and determine the gross and net requirements. All lead times are 1 week, and the quantities required are shown in parentheses. The master production schedule calls for the completion of 100 As in week 4 and 50 in week 5. There are 300 Bs scheduled to be received in week 1 and 200 Ds in week 3. There are also 20 As available. B(2) C(1) D(1) E(1) D(2) B(1) D(1) E(1) Low-Level Code 1 2 3 4 5 Part A Lead Time: 1 week Lot Size: lot-for-lot Part B Lead Time: 1 week Lot Size: lot-for-lot Part Lead Time: 1 week Lot Size: lot-for-lot Week Gross Requirements Scheduled Receipts Projected Available 20 Net Requirements Planned Order Receipt Planned Order Release Gross Requirements Scheduled Receipts Projected Available Net Requirements Planned Order Receipt Planned Order Release Gross Requirements Scheduled Receipts Projected Available Net Requirements Planned Order Receipt Planned Order Release Gross Requirements Scheduled Receipts Projected Available Net Requirements Planned Order Receipt Planned Order Release Gross Requirements Scheduled Receipts Projected Available Net Requirements Planned Order Receipt Planned Order Release Part D Lead Time: I week Lot Size: lot-for-lot Part E Lead Time: 1 week Lot Size: lot-for-lot