please show formula for solving b1

X-treme Vitamin Company is considering two investments, both of which cost $40,000. The cash flows are as follows: Use Appendix B for an approximate answer but calculate your final answer using the formula and financial calculator methocis. a-1. Calculate the payback period for Project A and Project B. (Round your answers to 2 decimal places.) a-2. Which of the two projects should be chosen based on the payback method? Droject A Project B b-1. Calculate the net present value for Project A and Project B. Assume a cost of capital \&f 12 percent. (Do not round intermediate calculations and round your final answers to 2 decimal places.)