Net present value method and present value index a. Determine the net present value for the two machines. Use the table of present values of an annuity of $1 above. Round to the nearest dollar. Feedback Check My Work each machine by the present value of an annuity factor for 8 periods at 15%, refer Exhibit 5 in the text. Subtract the amount to be invested. b. Divide the total present value of the net cash flow by the amount to be invested. c. What does the present value index indicate about the net present value