To find the surface area of a rectangular prism, you can use the formula:
\[ \text{Surface Area} = 2lw + 2lh + 2wh \]
where \( l \) is the length, \( w \) is the width, and \( h \) is the height of the prism.
From your description:
- Height (\( h \)) = 3 inches
- Width (\( w \)) = 12 inches
- Length (\( l \)) = 5 inches
Plugging these values into the formula:
\[ \text{Surface Area} = 2(5)(12) + 2(5)(3) + 2(12)(3) \]
Calculating each part:
- \( 2(5)(12) = 120 \)
- \( 2(5)(3) = 30 \)
- \( 2(12)(3) = 72 \)
Now add these together:
\[ \text{Surface Area} = 120 + 30 + 72 = 222 \]
Thus, the surface area of the rectangular prism is \( \textbf{222 square inches} \).