I can help, just explain the question and what you don’t understand!
Answer:
He showed that f(n) ÷ f(n - 1) was a constant ratio.
Given that Jake has proved that a function f(x) is a geometric sequence.
GEOMETRIC SEQUENCE: A geometric sequence is a sequence of numbers where each term is found by multiplying the preceding term by a constant called the common ratio, r.
So, in Jame's proof, he showed that each term is multiplied by a constant to get the next term.
That is, if 'c' is the constant that was used in the proof, then we must have
This implies that
Therefore, he showed that f(n) ÷ f(n - 1) was a constant ratio.
If by P=5ft you mean the radius is 5 then c = 2pi r or c = 10pi or approx 31.4 ft
The value would be 28,000*(1-0.0725)*(1-0.0725)*(1-0.0725)*(1-0.0725)*(1-0.0725)
which is 28,000*0,9275

which equals 28,000*0.6863=$19,219