I have the answers I just want the explanation and if you could make it applicable to my TI-84 calculator that would be great. Ex TvM solver and shortcuts on the calculator to get these answers instead of long formulas

6. What is the IRR of an investment that costs $77,500 and pays $27,500 a year for 4 years? A) 16% B) 18% C) 20% D) 22% E) 24% 7. What is the profitability index of the following investment if the required return 14%? Year Cash Flow S60 S15 $30 $45 A) 0.92 C) 1.13 D) 1.27 E) 1.93 8. What is the payback period for the following investment? Year Cash Flow -$85,000 $30,000 $20,000 $15,000 $10,000 0 2 4 A) 4 years B) 3 years 2 years D) 1 year E) The investment doesn't payback