A company must choose between two machines. Machine A costs $50 000 and the annual operating expenses are estimated to be $20 000, while Machine B costs $85 000 and has estimated annual operating expenses of $15 000. Both machines have a 10-year life and will have a zero residual value. Required: A. The company has a required rate of return of 10 per cent per annum. Which machine should it purchase? (15 marks) B. Rework the problem for a 7 per cent required rate of return. (14 marks)