Question

Two car washers, Michelle and Nancy, are working on your car. Michelle can complete the work in 6 hours, while Nancy can complete the work in 3 hours. How many hours does the car washing take if they work together?

Answer 1

Answer is 2 if they work together

Answer 2

Time taken by Michelle to complete the work alone = 6 hours
Time taken by Nancy to complete the work alone = 3 hours
Now, when they both are working on the same job for 1 hour, 
Amount of job completed = (1/6) + (1/3) 
                                         = (1 + 2)/6 
                                         = 3/6 
                                         = 1/2 
So in 1 hours time they both will complete half of the job. Then in 2 hours Michelle and Nancy will complete the total job. I hope the answer has come to your help.