A's copying alone took 10 days to complete a manuscript, and B's copying alone took 7.5 days to complete. Now the two teams are copying together, and A was out for a few days in the process. It took *

A's copying alone took 10 days to complete a manuscript, and B's copying alone took 7.5 days to complete. Now the two teams are copying together, and A was out for a few days in the process. It took *** 8 days to complete. Second

1. From the meaning of the question, A copies 1/10 of the total number every day, B copies 1/7.5 of the total number every day, and the two of them copy together 1/11/7.5=7/ 30

If two people copy together for 8 days, the completed quantity is 8*7/30=56/30, which is an extra 56/30—1=26/30

The extra 26/30 divided by A’s speed is the number of days that B can copy alone

A is out (26/30)/(1/10) = 26/3 days

Indeed, your topic is A and B for a while.

If B goes out for a period of time, then

B goes out (26/30)/(1/7.5) = 6.5 days

2.(1+ 1/15+2/33/18)/(1/15+1/31/18+1/45)=7.3125(days)