From the meaning of the question: x/60+2 (x+15)/60 =1. Multiply both sides by 60:x+2(x+ 15)= 60.

Solution: x = 10.

Answer: There are 10 people who arrange the sorting first. 2. Solution: Let's pump water for x hours from beginning to end.

From the meaning of the question: (1/24+1/30) x+1/40 (x-8) =1,and both sides are multiplied by120: (5+4) x+3.

Solution: x = 12.

A: From beginning to end, * * * pumping 12 hours. Topic: It takes 12 days for A to complete a job alone, and 6 days for B to do this job. Now A has done it for three days, and the rest of the work is done by A and B. How many days will it take to finish this work?

Solution: It takes X days to complete. The question means: 3/12+x/12+x/6 =1.

Solution: x=3