Thank you in advance :)

Barry Cabs is a sole proprietorship that owns and operates one taxi cab. The company purchased its cab 5 years ago for $40,000. When it purchased the cab it expected it to be useful for 8 years with a residual value of $5,000. Barry thinks he could sell the cab today for $14,000. Barry is considering replacing the old cab with a new, all-electric taxi. The all electric car would cost $60,000 and would have an expected useful life of 8 years. Over its 8 year life, the cab would reduce annual operating costs (mostly gas and maintenance) by $8,000 per year for the first 6 years, and $10,000 per year thereafter. After 8 years, it is expected the taxi would have a $2,000 residual value. Barry's cost of borrowing is 15% and assume no tax implications Required: 1 What is the payback period for replacing the exiting cab with the new electric taxi? (2 marks) 2 What is the net present value of replacing the existing cab with the new electric one? (4 marks) 3 What is the internal rate of return for replacing the existing cab with the new electric one? (2 marks) 4 What is the profitability index for replacing the existing cab with the new electric one? (2 marks)