2 train-lines leave the same central station at the same time.
line 1: f(x) = 6000 + 50x
line 2: g(y) = 2000 + 50y
x and y are the number of departures pr. hour. line 1 can have 2 departures pr. hour pr. trian, and line 2 can only have 1 departure pr. hour pr. train.
There is a total of...