Can I get help with the below

What is a schedule of accounts payable? How is this useful for companies to review and how often do you feel it should be looked at?

What is the difference of buying supplies for the office and purchases for a merchandising company? Why is it required that you keep track of your purchases?

What is the formula for cost of goods sold for a merchandising or manufacturing company? How does this week's chapter on accounts payable and purchases play a role in this calculation?