Sally can paint a room in 6 hours while it takes Steve 9 hou

Sally can paint a room in 6 hours while it takes Steve 9 hours to paint the same room. How long would it take them to paint the room if they worked together?

Solution

Given that

Sally can paint a room in 6 hours

   Sally can paint a room in 1 hour = 1/6

  Steve 9 hours to paint the same room

    Steve can paint a same room in 1 hour = 1/9

  Sally and Steve worked together can paint a room in 1 hour = 1/6 + 1/9

= (6 + 4)/36

= 10/36

Sally and Steve worked together can paint a room in 1 hour = 5/18

Hence ,

    Sally and Steve worked together can paint a room = 18/5