The monthly payment R on a loan is a function of the amount borrowed, A, in thousands of dollars; the length of the loan, n, in years; and the annual interest rate, r, as a percent. Thus R = f (A, n, r). In parts (a) and (b), write a sentence that explains the practical meaning of each mathematical statement.

(a) f (94.5, 25, 7) = $667.91

(b) ∂f/∂r (94.5, 25, 7) = $60.28

(c) Would ∂f/∂n (94.5, 25, 7) be positive, negative, or zero? Explain.