I just kind of sat here playing with numbers i dont really know a shortcut but the answer is 10 chickens and 15 rabbits
10*2= 20 each chicken has two legs so thats 10 heads 20 legs
15*4=60 each rabbit has four legs so thats 15 heads 60 legs
15+10=25 heads
20+60=60 legs
The answer to the question is range
X=67
___
20
??? Is that what you needed idk lol