You know right off that chickens have 2 legs and rabbits have 4 legs.
If all 22 legs belonged to chickens, then there would be 11 animals, since 2 X 11 = 22.
But there were only 8 animals.
That means you'll need to trade in some chickens for rabbits.
You can also try drawing a picture to help you.
Click here if you'd like more help.