SOLUTION: tom can paint a room in 5 hours, steve can paint the same room in 10 hours and Mary can paint the same room in 20 hours. If they work together, how long will it take them to paint

Algebra ->  Rate-of-work-word-problems -> SOLUTION: tom can paint a room in 5 hours, steve can paint the same room in 10 hours and Mary can paint the same room in 20 hours. If they work together, how long will it take them to paint       Log On


   

Question 393825: tom can paint a room in 5 hours, steve can paint the same room in 10 hours and Mary can paint the same room in 20 hours. If they work together, how long will it take them to paint the room?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

Let x represent time in hours together

Question state***per hour being the equalizer

 1/5 + 1/10 + 1/20 = 1/x  |multiplying thru with 20x so as all denominators = 1

 4x + 2x + x = 20

          7x = 20

           x = 20/7 hrs, time in hours together