Answer:
860cm²
Step-by-step explanation:
1. area of the side triangle:
(15×8)×2= 120×2= 240cm²
there's two side triangles with the same length and width, so just multiply by two.
2. area of the square on top:
20×8= 160cm²
3. area of the rectangle behind:
20×8= 160cm²
4. area of the square below:
20×15= 300cm²
5. the total of all areas (surface area):
240+160+160+300= 860cm²
