Question
A bullet train had some passengers at the beginning. After 21 passengers alighted from the bullet train and another 45 passengers boarded the bullet train, there were 3 times as many passengers as before. How many passengers were there on the bullet train at first?
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A bullet train had some passengers at the beginning. After 21 passengers alighted from the bullet train and another 45 passengers boarded the bullet train, there were 3 times as many passengers as before. How many passengers were there on the bullet train at first?