The amortization formula applies. A = P*(r/n)/(1 -(1 +r/n)^-(nt)) where A is the payment in each compounding period (820) P is the principal amount (present value) r is the annual interest rate (.05) n is the number of compoundings per year (2) t is the number of years (14)
Filling in the numbers, we have 820 = P*(.05/2)/(1 -(1 +.05/2)^-(2*14)) 820 = .025P/(1 -1.025^-28) P = 820(1 -1.025^-28)/.025 P ≈ 16,371.21
The present value of that string of payments is $16,371.21.