Y Ltd has received two offers for a new computer system. System P will cost $200,000 now, has a three year life and costs $10,000 a year to operate. System Q costs $240,000 now, has a four year life and costs $12,000 a year to operate. The relevant discount rate is 6 per cent per annum. Ignoring depreciation and taxes, calculate the AEC for each. Which do you prefer, and why?