If the train between a and B stops at three stations, there will be______ Different fares (same round-trip fare) need to be prepared______ I want to buy a ticket

If the train between a and B stops at three stations, there will be______ Different fares (same round-trip fare) need to be prepared______ I want to buy a ticket


This question is equivalent to how many different fares there are in a line segment with three points, that is, how many lines there are: 4 + 3 + 2 + 1 = 10; how many kinds of tickets need to be considered in order, 10 × 2 = 20



If the train between a and B stops at three stations, there will be______ Different fares (same round-trip fare) need to be prepared______ I want to buy a ticket


This question is equivalent to how many different fares there are in a line segment with three points, that is, how many lines there are: 4 + 3 + 2 + 1 = 10; how many kinds of tickets need to be considered in order, 10 × 2 = 20