In your text, section $4\mathrm{.}1$ in pages $99-111$ gives you're an example why one who starts business may take a business loan. The case treats what happens when you purchase and sell an item, when the sale price is larger of lower to the purchase price, when you borrow some or a lot or nothing at a given interest rate, when you purchase and sell one or many items. The text does not evaluate the profit or loss in dollars, it gives only a profit$/$loss rate.

I ask you to reproduce the problem in EXCEL where you can integrate everything that it is in the book into ONE only set, that allows you to control your calculations with the changing variables. What may happen if you purchase several items and you sell different quantities at various prices. Why and when do you lower the selling price?

What do you learn from this section about the borrowing process in business?