Lindsay can paint 1/x of a certain room in one hour. If Lindsay and Joseph, working together at their respective rates, can paint the room in two hours, what fraction of the room can Joseph paint in 20 minutes?	Choices:	A) 1/6x	B) x/(x-6)	C) (x-2)/6x	D) x/(x-2)	E) (x-2)/x
Let J be Joseph's rate per hour.   1/x + J = 1/2 of a room per hour   J = 1/2 - 1/x, of a room per hour   In 20 minutes Joseph can paint 1/3*(1/2-1/x) = 1/6-1/3x = (x-2)/6x   The answer is (x-2)/6x.
<result>C</result>
Lindsay can paint 1/x of a certain room in one hour. If Lindsay and Joseph, working together at their respective rates, can paint the room in two hours, what fraction of the room can Joseph paint in 20 minutes?