passengers got on at Monkey House. At Alligator Pond, the number of people

who got on was 3 more than got on at Monkey House.

The train made 4 more stops at Tiger Thicket, Panda Playground, Giraffe

Savannah, and Big Cats. At each of these stops, 3 more passengers boarded

the train than at the previous stop. At Big Cats, 20 people got on the train.

How many passengers in all boarded the train?

Answer using the comments section below. Be sure to explain your thinking.