Answer:
248

Explanation:
Instead of calculating for the hexagon, divide it into 5 separate triangles with a 8mm base and 5.5mm height. Calculate using the "half base times height" formula and multiply it by five for the hexagon's area:

This is the area of the pentagonal pyramid's base. Now for the sides calculate the area of an individual side (triangle with base 8mm and height 6.9mm) then multiply by 5 for the area of all the sides:

For the total surface area of this shape add these values together for 110+138=248mm

I hope that this helps :)