Question

sue, an experienced shipping clerk, can fill a ertain order 9 hours. Jim, a new clerk, needs 10 hours to do the same job. working together how long will it take them to fill the order?

Answer 1

Let x be the time required to do the job when they work together.
1/x = 1/9 + 1/10 = 19/90
x = 90/19 = 4.7 hours