How do you create a basic Cost Calculator app in Xcode for IOS App Development?

For example, you want to do an app that gives you the cost of buying airplane tickets from one city to another. The starting city will always be Durant. You have three pricings:

Durant to Dallas: $39.99

Durant to Las Vegas: $59.99

Durant to New York: $79.99

You need three buttons, one for Dallas, Las Vegas, and New York. You also need a text box where you can input the number of tickets you want to buy. Then beneath that is a calculate button to get the total cost. So, for example, you click the Dallas button, which has tickets at 39.99 each. In the text box, you type 2. The calculate button would need to then display the total price, in this case, 39.99 x 2.

How do you build this app?