Here's the solution,
Surface area :
=》
[tex] \boxed{\mathbf { \footnotesize (2 × area \: of \: triangle) + (3 × area \: of \: rectangle) }}[/tex]
=》
[tex] (2 \times \dfrac{1}{2} \times 8 \times 3) + (3 \times 12 \times 5)[/tex]
=》
[tex]24 + 180[/tex]
=》
[tex]204[/tex]
surface area = 204 cm²
