can someone plewse solve asap? a,b,c are all part of one question! thank you

An investment has an installed cost of $524,800. The cash flows over the four-year life of the investment are projected to be $224,850,$241,450,$208,110, and $156,820, respectively. a. If the discount rate is zero, what is the NPV? (Do not round intermediate calculations.) b. If the discount rate is infinite, what is the NPV? (A negative answer should be indicated by a minus sign.) c. At what discount rate is the NPV just equal to zero? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.)