Question: If every second, a bubbling spring creates a new jellyfish, how many jellyfish would 5 springs working at the same rate create in 4 hours?
Work out the solution step by step. 
Answer: 
Since an hour has 3600 seconds, if every second, a bubbling spring creates a new jellyfish, it will create 4*3600 = 14400 jellyfish in four hours.
Five springs working at the same rate will create 14400*5 =72000 jellyfish in four hours.