SOLUTION: Lisa and Kay were asked by their mother to clean their room. Lisa can clean her room in 8 hours, and Kay in 12 hours. How long will it take if they both clean their room together?

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Question 703856: Lisa and Kay were asked by their mother to clean their room. Lisa can clean her room in 8 hours, and Kay in 12 hours. How long will it take if they both clean their room together?
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Lisa and Kay were asked by their mother to clean their room. Lisa can clean her room in 8 hours, and Kay in 12 hours. How long will it take if they both clean their room together?
Let x = time (hours) for both working together
then
x(1/8 + 1/12) = 1
multiplying both sides by 24:
x(3 + 2) = 24
x(5) = 24
x = 24/5
x = 4.8 hours
or
x = 4 hours and 48 minutes