JKL Enterprises is evaluating the purchase of new equipment. The equipment costs GBP 350,000 and has an expected useful life of 5 years, with a salvage value of GBP 30,000. Depreciation will be calculated using the straight-line method. The company's cost of capital is 13%. Expected cash flows and profits are as follows:

Year	Cash Flow	Profit
1	£40,000	£5,000
2	£45,000	£10,000
3	£50,000	£15,000
4	£55,000	£20,000
5	£60,000	£25,000

Requirements: a) Explain the concept of relevant costs in investment appraisal. b) Compare and contrast the payback period and net present value (NPV) methods. c) Calculate the following using the data provided: i) The payback period. ii) The NPV. iii) Recommend whether JKL Enterprises should proceed with the purchase of the equipment.