Question 1042213
.
9 ft x 3 ft.


For details on how to solve it and how to get the answer, see the lesson 
<A HREF=https://www.algebra.com/algebra/homework/Surface-area/Problems-on-the-area-and-the-perimeter-of-a-rectangle.lesson>Problems on the area and the perimeter of a rectangle</A> in this site.