Extra Terrestrial Puzzle

The Puzzle:

Extra Terrestrial
Remember the film? Well this puzzle has got nothing to do with it.

On the planet Glogg, the inhabitants are similar to human beings, however they differ in one respect -

they either have 3 heads and the normal amount of arms and legs (known as HEADERS) OR

they have one head and 3 legs and 3 arms (known as LEGGERS).

Last week, I was talking to a group of friends from the planet and between them they had 15 heads and 48 limbs. How many headers and how many leggers were there?
Do you have the answer? Check against our solution!