Please study the Virgin Trains network map [below] which clearly displays a straight line route between Glasgow Central and London Euston.
All trains on this straight line route [between Glasgow Central and London Euston] may stop at any of the intervening stations so that passengers may board or leave the train.
A recent survey stated 500 passengers arrived at London Euston on a Virgin train from Glasgow Central.
Can you calculate how many of these 500 passengers boarded the train at Glasgow Central?
Can you calculate how many passengers left the train before it arrived at London Euston?
Can you calculate how many passengers boarded the train after it left Glasgow Central?