11, -8, and 7 are the answers...
Please mark as brainliest... I really need it...
Hello,
Using Thalès 's theorem:
Let's h the height of the monument.

If you don't know what is the Thalès's theorem,
imagine that the similar triangles.
2(20 x 10) + 2(10 x 5) + 2(20 x 5)
2(200) + 2(50) + 2(100)
400 + 100 + 200
400 + 300
700
There are 700 square feet for the surface area