Answer: 81 ft^2
Hello! The surface area of the rectangular prism will follow this process:
Right triangle area: (1/2)bh
So that 6ft (4.5ft) = 27ft^2/2; though when one multiplies that by 2 (as there are two right triangles), we get a surface area of 27ft^2.
For the rectangle's area, it's slightly more deviated since each face is different in length: bh
Face 1 = 3ft(7.5ft) = 22.5ft^2
Face 2 = 3ft(6ft) = 18ft^2
Face 3 = 4.5ft(3ft) = 13.5 ft^2
Thus, if we add these all together (27ft^2. + 22.5ft^2 + 18ft^2 + 13.5 ft^2), we get 81 ft^2