To find the surface area, we want to find the area of each side, then add them all up together:
Area of base=lw
A=(5)(5)
A=25 cm²
Area of triangle=1/2bh
A=(1/2)(5)(12.5)
A=31.25 cm²
Since the 4 triangles have the same area, we can multiply the area we found by 4 and then add the area of the square:
SA=(4)(31.25) + 25
SA=125+25
SA=150 cm²