Test Your Brain- Answer

Two shaggy old dogs were walking down the street. Captain sits down and scratches his ear, then turns to Champ and growls, "If one of your fleas jumped onto me, we'd have the same number."

Champ barks back, "But if one of yours jumped onto me, I'd have five times as many as you!"

How many fleas are there on Champ?

Captain has two fleas and Champ has four