Answer:
The height of the wall is 18 ft.
Step-by-step explanation:
I have taken a look at the question, and will label the diagram accordingly. Check the attachment.
We are asked to calculate the height of the wall. Well, the incidence ray is equal to the reflected ray, so therefore by AA we have similar triangles. Setting up a proportion to determine the height of the wall:
9/6 = 27/x [where x = height of the wall]
x = 27*6/9 = 18 ft.