Generally, the total amount of the project should be set as 1, and then, for example, I tell you that it takes three days for A to complete a project, so what A does in one day is 1/3, what B does in one day is 1/X, and then he says that A works for two days first, and then works with B for three days before it can be completed. Then A * * * did (2+3) and13 in one day, so A * * * did (2+3)/3. Otsuichi * * * worked for three days and 1/x in one day, so a * * * did 3/x, how much work did A and B do? Of course, the total term is 1, so the equation (2+3)/3+3/x= 1 can be listed.

This type of question is generally used, and other types of questions will be analyzed in detail.

The step is very simple, that is, write: solution: suppose it takes X days for B to finish it alone.

Then write the equation directly.

Then calculate x on paper and write directly on paper: What is the solution of X=

Don't forget to write down the solution of the original equation when x= after the exam.

Then you can write the answer.

Cheko is here, I hope I can help you ~