If Party A works alone for 15 hours and Party B works alone for 12 hours, if Party A works alone for 1 hour and has worked alone for 4 hours, the remaining work can be completed in a few hours with the cooperation of two people

If Party A works alone for 15 hours and Party B works alone for 12 hours, if Party A works alone for 1 hour and has worked alone for 4 hours, the remaining work can be completed in a few hours with the cooperation of two people

It will take another x hours
be
1/15(1+X)+1/12(4+X)=1
Solution
X=4

For a task, party a completed 2 / 3 of it in 1 / 4 hour. According to this calculation, if all of it is completed, how many hours will it take

1÷（2/3÷1/4）
=1÷8/3
=3 / 8 (hours)
A: it takes 3 / 8 hours

One twelfth of a work can be completed in four days, and () can be completed every day. According to this calculation, how many days will it take to complete all the work?

It takes 48 days to complete all the work