To calculate 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 numbers, we can assign:
- \( l = 10 \)
- \( w = 3 \)
- \( h = 9 \)
Now, substituting these values into the surface area formula:
\[ \text{Surface Area} = 2(10)(3) + 2(10)(9) + 2(3)(9) \]
Calculating each term step-by-step:
- \( 2(10)(3) = 60 \)
- \( 2(10)(9) = 180 \)
- \( 2(3)(9) = 54 \)
Now, add these results together:
\[ \text{Surface Area} = 60 + 180 + 54 = 294 \]
Thus, the surface area of the rectangular prism is \( \boxed{294} \) square units.