Answer:
a) See figure attached
b)

c)

So then the heigth for the building is approximately 30 ft
Explanation:
Part a
We can see the figure attached is a illustration for the problem on this case.
Part b
For this case we can use the sin law to find the value of r first like this:


Then we can use the same law in order to find the valueof x liek this:


And that represent the distance between Sara and Paul.
Part c
For this cas we are interested on the height h on the figure attached. We can use the sine indentity in order to find it.

And if we solve for h we got:

So then the heigth for the building is approximately 30 ft