Question 3663
This is simular to the one I answered earlier...

There are 3 feet in a yard. 

The width of the room in feet is:  3*W
The length of the room in feet is: 3*L
The area of the room in square feet is:  (3*W)(3*L)=9WL
The cost is $.10 * 9WL = $.90WL 
This makes sense because it equates to 90 cents a square yard and there are 9 square feet in a square yard.