There is length, width and height
Length=L
Width=W
Height=H
We can make this equation to solve the surface area of a rectangular prism.
(L*W*2)+(L*H*2)+(H*W*2)=SA (Surface Area)
For this specific problem, the equation is:
(15*12*2)+(15*6*2)+(12*6*2)
We can use the calculator to find this out
$$\left({\mathtt{15}}{\mathtt{\,\times\,}}{\mathtt{12}}{\mathtt{\,\times\,}}{\mathtt{2}}\right){\mathtt{\,\small\textbf+\,}}\left({\mathtt{15}}{\mathtt{\,\times\,}}{\mathtt{6}}{\mathtt{\,\times\,}}{\mathtt{2}}\right){\mathtt{\,\small\textbf+\,}}\left({\mathtt{12}}{\mathtt{\,\times\,}}{\mathtt{6}}{\mathtt{\,\times\,}}{\mathtt{2}}\right) = {\mathtt{684}}$$
The surface are for this problem is 684 ft^2
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