To find the surface area of a rectangular prism, you can use the formula:
\[ \text{Surface Area} = 2(lw + lh + wh) \]
where \( l \) is the length, \( w \) is the width, and \( h \) is the height.
Given the dimensions:
- Length \( l = 12 \) inches
- Width \( w = 5 \) inches
- Height \( h = 3 \) inches
Let's calculate each term in the formula:
- \( lw = 12 \times 5 = 60 \)
- \( lh = 12 \times 3 = 36 \)
- \( wh = 5 \times 3 = 15 \)
Now, substitute these values back into the surface area formula:
\[ \text{Surface Area} = 2(60 + 36 + 15) \]
First, calculate the sum inside the parentheses:
\[ 60 + 36 + 15 = 111 \]
Now, multiply by 2:
\[ \text{Surface Area} = 2 \times 111 = 222 \text{ square inches} \]
Therefore, the surface area of the rectangular prism is 222 square inches.