At the first pick-up point, the number of people who entered the bus was 3/5 of its carrying capacity, a total of 3/5*80 = <<3/5*80=48>>48
The available seats in the bus after the first pick up point is 80-48 = <<80-48=32>>32
If there were 50 people in the second pick-up station, and only 32 sits were available, the number of people who did not take the bus because it was full is 50-32=<<50-32=18>>18
#### 18