Hey there! :)
You have to find the area of all of them and add it together.
Formulas:
Area of a square: l · w
Area of a triangle: (b · h) ÷ 2
Square -
l = 3
w = 3
3 × 3 = 9
Triangle -
b = 3
h = 3
(3 × 3) ÷ 2
9 ÷ 2 = 4.5
There are 4 triangles
4.5 × 4 = 18
9 + 18 = 27
The surface area ⇒ 27 cm²
