two people can clean the house in 3 and 6 hours. they have agreed to clean together. How long will it take them to clean the house working together

Question

working alone, two people can clean the house in 3 hours and 6 hours, respectively. they have agreed to clean together. How long will it take them to clean the house working together

Answer 1

1/3 = portion of job done by the first person per hour

1/6 = portion of job done by the second person per hour

 

If x = number of hours it takes to do the job if they both work together, then

 

   1/3 + 1/6 = 1/x

 

            1/2 = 1/x     So, x = 2 hours