You can just use sine.
Sin(F) = opposite/hypotenuse = 28/40.
F =

(28/40)
Plug into your calculator.
44.4
Step-by-step explanation:
you did not show us the graph, and your problem description is a bit gibberish - I am sure there are some important parts missing.
therefore it is impossible to answer this.
There are 10 bird feeders in total. So if Bob builds 10 Jake builds 0. If Bob builds 9 then Jake builds 1. If Bob builds 8 then Jake builds 2 and so on.