b. The cash payback period. c. The net present value. Use the above table of the present value of an annuity of $1. Round to the nearest dollar. If required, use a minus sign to indicate negative net present value" for current grading purpose. Present value of annual net cash flows Less amount to be invested Net present value b. The cash payback period. c. The net present value. Use the above table of the present value of an annuity of $1. Round to the nearest dollar. If required, use a minus sign to indicate negative net present value" for current grading purpose. Present value of annual net cash flows Less amount to be invested Net present value