It is not always possible to divide several objects evenly among a certain number of objects. If an object has surplus, it is called surplus; If the object is not divided enough, it is called a loss. Any research on the application of profit and loss algorithm is called profit and loss problem.

Profit and loss problem formula:

1, a surplus (surplus), a deficit (deficit), the formula can be used: (surplus+deficit) ÷ (difference between two distributions per person/big point-small point) = number of people;

2. There are two surpluses (surpluses), and the formula can be used as follows: (large surplus-small surplus) ÷ (difference between two distributions per person/large score-small score) = number of people;

3, twice is not enough (loss), the formula can be used: (big loss-small loss) ÷ (difference between two per capita distributions/big point-small point) = number of people;

4, one time is not enough (loss), and the other time has just finished. The formula can be used: loss ÷ (difference/big point-small point of twice distribution per person) = number of people;

5. One time it was surplus, and the other time it was just eaten. The formula can be used: surplus ÷ (the difference between two distributions per person/big point-small point) = number of people.

A parts factory pays wages according to the qualified parts and unqualified parts completed by workers. Workers get 10 yuan for manufacturing a qualified part every day, and 5 yuan will be deducted for each unqualified part. It is known that someone works 12 jobs a day, and the salary is 90 yuan. So how many unqualified parts did he make on this day? Assuming all qualified, you should earn 120 yuan, that is, 65438+ is less than 30 yuan. 30/( 10+5)=2;