****Please show work, so, I can grasp the concept*****

Please explain what these numbers mean in terms of making predictions regarding inventory?

How many units are available-to-promise in period 1? period 4? PERIOD ON HAND = 60 1 2 3 4 5 6 Forecast 50 100 100 100 100 50 Customer Orders 85 125 95 85 45 15 Master Production Schedule 250 250 Available-to-Promise 4.23 How many units are available-to-promise in period 1? period 4? Period Forecast CO MPS ATP 1 50 85 250 2 100 125 3 100 95 4 100 85 250 5 100 45 6 50 15