Answer:
39

Explanation:
Area of a triangle =
× base × height
All four triangles are similar. So finding the area of one triangle, will be the area of the other triangles.
× 3 × 5 = 7.5

∴ The area of 4 triangles are 7.5 × 4 = 30

Then the only shape remaining is the square.
Area of the square =
(all the sides of a square are equal)
=
= 9

Total surface area = 30 + 9 = 39
