please solve using a financial calculator and what keys used

Consider the following cash flows: a. What is the NPV at a discount rate of zero percent? Note: Do not round intermediate calculations and round your answer to the nearest whole number, e.g., 32. b. What is the NPV at a discount rate of 8 percent? Note: Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16 . c. What is the NPV at a discount rate of 18 percent? Note: A negative answer should be indicated by a minus sign. Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16. d. What is the NPV at a discount rate of 28 percent? Note: A negative answer should be indicated by a minus sign. Do not round intermediate calculations and round your answer to 2 decimal places, e.g., 32.16