Answer:
Total surface area of the given figure is 246.75 square mile.
Explanation:
Surface Area of the given figure = Lateral surface area + Area of the base
Lateral surface area of the figure = Sum of the areas of 5 triangular surfaces
=

=

= 162.75 mi²
Surface area of the pentagonal base = 84 mi²
Total surface area of the figure = 162.75 + 84
= 246.75 mi²
Therefore, total surface area of the given figure is 246.75 square mile.