We are teaching you skills to solve the following types of chicken and rabbits problems:

(1) Given the sum of heads and the sum of legs, find the
number of animals of each type.

(2) Given the difference of heads and the sum of legs, find
the number of animals of each type.

(3) Given the difference of legs and the sum of heads, find
the number of animals of each type.

(4) Given the difference of heads and the difference of
legs, find the number of animals of each type.

(5) There are problems similar to chickens and rabbits problems
above but with three or four animals at Old Macdonald's farm.

(6) There are problems similar to chickens and rabbits
problems above but with different things like three-leg stools and four-leg
tables, bicycles and tricycles, octopus and sea otters, cows and ducks, spiders
and dragonflies.