Calculate the net present value at year 0 for the following cash flows and interest rates compounded semi-annually (rounded $ to two places after the decimal). The year 0 cash flow is $[a], the year 1 cash flow is $[b], and the year 2 cash flow is $[c]. The interest rate for the first period (year 0 to 1) is [x]% and the interest rate for the second period (year 1 to 2) is [y]%.