operation research course. please explaine the answer and the steps

1. An Example Imagine that you have a 5-week business commitment between Istanbul (IST) and Ankara (ESB). You fly out of Istanbul on Monday and return on Wednesday. A regular round-trip ticket costs 500TL, but a 20% discount is granted if the dates of the ticket span a weekend. A one-way ticket in either direction costs 75% of the regular roundtrip price. How should you buy the tickets for the 5-week period? We can look at the situation as a decision-making problem whose solution requires identifying three main components: (a) What are the decision alternatives? (b) Under what restrictions is the decision made? (c) What is an appropriate objective criterion for evaluating the alternatives? The following alternatives are available for purchasing the tickets: (a) Buy five regular IST-ESB-IST, (b) Buy one IST-ESB, four ESB-IST-ESB that span weekends, and one ESB-IST; (c) Buy one IST-ESB-IST to cover Monday of the first week and Wednesday of the last week and four ESB-IST-ESB that span weekends to cover the remaining legs. The restriction on these options is that you should be able to leave on Monday and return on Wednesday of the same week