Method 1:
(total number of feet-number of chicken feet × number of chickens) ÷ (number of rabbit feet-number of chicken feet) = number of rabbits.
Suppose rabbits are all chickens, and 1 has four feet. Imagine it as a chicken with two feet. Each rabbit is missing two feet, and * * * is missing one foot. There are several 2' s in A, which means several rabbits.
Total number-rabbit number = chicken number.
Method 2:
(number of rabbit feet × total feet-total feet) ÷ (number of rabbit feet-number of chicken feet) = number of chicken feet.
Suppose all chickens are rabbits, and 1 has two feet. If we think of it as a rabbit with four feet, then each chicken will have two more feet, counting one foot, and how many twos there are in A, that is, how many chickens.
Total number-number of chickens = number of rabbits.