To find the surface area of the desing you need to find the are for all of the faces of the figure.
at the bottom we have a rectangular prism of sides 10, 10 and 2
sind the top, bottom and sides os this prism
![\begin{gathered} \text{top and bottom} \\ 2\cdot10in\cdot10in=200in^2 \\ \text{sides } \\ 4\cdot10in\cdot2in^2=80in^2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8kp48s3bmywjp9ou9pl4rimbnonqg4h1gt.png)
total surface area at the bottom prism
![200+80=280in^2](https://img.qammunity.org/2023/formulas/mathematics/college/clplvhnw5usdxktaivp4de3up30evkux2b.png)
for the prism at the top we just add the area from the sides because the top was already considered at the top of the previous prism
![\begin{gathered} \text{sides} \\ 4\cdot8in\cdot5in=160in^2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/3ie9g93va9cfmzxw2jl9k4uj5q4c764lt7.png)
total surface are of the design is
![280+160=440in^2](https://img.qammunity.org/2023/formulas/mathematics/college/o7pvam9gbolavtuiant810elbi8lsv2qeq.png)