We have that the total surface area of the rectangular prism is:
[tex]\begin{gathered} A_T=\text{ 2(4.5ft }\cdot\text{ 4ft) + 2(4.5 ft }\cdot\text{ 2ft)} \\ =2(18ft^2)+2(9ft^2) \\ =36ft^2+18ft^2 \\ =54ft^2 \end{gathered}[/tex]So the answer is 54 ft^2.