Sara can write a paper in 5 hours and Jasmin takes 7 hours. How long will it take the two of them writing together?

2 answers

Writing a paper is not like painting a wall. There have to be agreements about what is to be written, which takes more time. I would not know how to figure this out.
I agree with PsyDAG

Your question makes about as much sense as this one:

Sara can drive to Chicago in 5 hours, Jasmin can do the same trip in 7 hours. How long will it take the two of them driving together?