Test 1.
Need three tickets -> 3 * 4 = 12
And need money (two tickets) for first pessenger for distance from 1 to 4.
All sum = 12 + 2 * 4 = 20.

Please, tell me, what I dont understand.

Sorry, I bad speak english.

this not test 1, example test!!!
From 1 to 4: 3 ticket
Two people in 4 don't need!
3*4=12