(total number of feet-number of feet per chicken × total number of heads) ÷ (number of feet per rabbit-number of feet per chicken) = number of rabbits;

Or (number of feet per rabbit × total head-total feet) ÷ (number of feet per rabbit-number of feet per chicken) = number of chickens;

(2) Given the difference between the total number of chickens and the number of rabbits, when the total number of chickens is greater than the total number of rabbits, the formula (the difference between the number of chickens × the total number of cephalopods) ÷ (the number of chickens+the number of rabbits) = the number of rabbits; Or (the number of feet per rabbit × the total number of heads+the difference between the number of feet of chickens and rabbits) ÷ (the number of feet per chicken+the number of feet exempted from each chicken) = the number of chickens;

(3) Given the difference between the total number of feet of chickens and rabbits, when the total number of feet of rabbits is greater than that of chickens, the formula can be used. (the number of feet per chicken × the total number of heads+the difference between the number of feet of chickens and rabbits) ÷ (the number of feet per chicken+the number of feet per rabbit) = the number of rabbits;

Or (the number of feet per rabbit × the total number of heads-the difference between the number of feet of chickens and rabbits) ÷ (the number of feet per chicken+the number of feet per rabbit) = the number of chickens;

(4) The following formula can be used to solve the gain and loss problem (the generalization of the chicken-rabbit problem):

(65438 points +0 number of qualified products × total number of products-total score obtained) ÷ (score of each qualified product+deduction of each unqualified product) = number of unqualified products. Or total number of products-(points deducted for each unqualified product × total number of products+total score obtained) ÷ (points deducted for each qualified product+points deducted for each unqualified product) = number of unqualified products.

(5) The problem of chicken and rabbit exchange (the problem of finding the number of chickens and rabbits after the total number of feet is known) can be solved by the following formula: [(sum of two total feet) ÷ (sum of feet of each chicken and rabbit)+(difference of two total feet) ÷ (difference of feet of each chicken and rabbit)] ÷ 2 = number of chickens. ⊙ (sum of total feet twice) ⊙ (sum of feet of each chicken and rabbit)-(difference of total feet twice) ⊙ (difference of feet of each chicken and rabbit) ⊙2 = number of rabbits.