There are n stations on a railway line. The number of kinds of tickets printed (no return tickets) is 105. Find the number of stations

There are 50 stations on a railway line.The number of different kinds of single 2 nd class tickets must be printed so as to enable a passenger to travel from one station to another station is:

There are n stations in a railway line.The number of way of choosing r stations such that no two of them are consecutive is

There are five stations on a railway line. What is the number of different journey tickets that are required for railway authorities?

On a railway route there are 20 stations. What is the number of different tickets required in order that it may be possible to travel from every station to every other station

On a raiway there are 10 stations. The number of types of tickets required in order that it may be possible to book a passenger from every staton to every other is

There are 15 stations on a certain railway line. How many different types of tickets must be printed so that a passenger can travel from any station to another in that line?

On a railway there are 20 stations.The number of different tickets required in order that it may be possible to travel from every station to every station is