please explain how we get the MPS, PI and ATP showed in the table

Assume every month has four weeks January demand is 200 February demand is 300 Beginning inventory is 54 Lot size is 150 Firm planned orders for the first six weeks are: 50, 38, 22, 18, 6, and 2 The remaining two weeks do not have any firm orders Develop a master production schedule. Question 116 What is the scheduled production level for period 1? (Not all periods will have production scheduled. For periods without production, enter a zero.) Answer: X (0) Hide Feedback January 50 38 Forecast Customer orders Inventory before MPS MPS Projected inventory -46 -296 150 u ATP Question 117 What is the scheduled production level for period 2