Sam sells sandwiches in a shop that he owns. Unfortunately, he did not check his stock
carefully last night and has arrived at the shop this morning to find that he has only got
enough bread to make 30 sandwiches. He can contact his usual supplier, who will be
able to deliver the bread in three hours for the normal price. Alternatively, the supplier -
will deliver the bread in one hour if Sam is willing to pay an additional $10. Sam's other
option is to buy the bread from the supermarket next door, but that will cost $20 more
than the price that he usually pays. Sam normally expects to be able to sell 20 sandwiches ever hour, but customers who cannot get a sandwich when they come into the shop will not wait. When the ingredients are bought at the normal price, Sam makes a profit of $1 for each sandwich that he sells. Which option for getting bread should Sam adopt in order to maximize his profit?