On Children's Day, I bought two series of books, The Mystery of Space and Sea World, and used them in 240 yuan. The price of space mystery series books is three-fifths of that of Sea World. How much is a set of sea world books?

Solution: If the price of Sea World series is X yuan, the price of Space Mystery series is 3/5x yuan.

x+3/5x=240

8/5x=240

x= 150

A: The price of Sea World Series 1 is 150 yuan.