please explain how to calculate ATP, I saw someone answer this question but they did not explain how they got the answer

Q1 The chart below shows the Master Production Schedule (MPS) and committed customer orders for a new MP3 Player you manufacture. Based on this information calculate Available to Promise (ATP.) Q2 To make your product you use 2 machines in sequence, machine A first for 15 minutes and then machine B for 20 minutes. You're currently using a chase production strategy and demand is expect to be 450 this month and 500 next month. a) What is your production plan each month? b) Which machine is the bottleneck? c) Given the bottle neck, how many units can you produce in an hour (assume when you start producing there is WIP in front of each machine.) d) Assuming 20 work days in a month and 8 hours per work day, is your production plan feasible? (it must be feasible for both months). Explain why or why not. e) If your plan is not feasible, what changes to the plan do you advocate