How many different fares are there? How many kinds of tickets do you need to prepare?

How many different fares are there? How many kinds of tickets do you need to prepare?

There are 10 kinds of fares for 2 stations selected from 5 stations
There are two kinds of starting and ending points for each ticket, and a total of 20 kinds of tickets need to be prepared

The bus between a and B stops at four stops______ What are the different fares? (2) Be prepared______ What kind of ticket?

According to the definition of line segment, there are 10 line segments in the graph, including AC, ad, AE, AB, CD, CE, CB, De, DB and EB. (1) there are 10 different ticket prices. (2) because the ticket needs to consider the direction, for example, "a → C" and "C → a" tickets are the same, but the tickets are different, so 20 kinds of tickets need to be prepared