(a) An engineer has received two bids for an elevator to be installed in a new building. The bids, plus his evaluation of the elevators, are as follows: Engineer's evaluation Alternative Bid Service life Annual Salvage value (year) operating cost Westinghouse 45,000 10 2,700 3,000 Itis 54,000 15 2,850 4,500 If the interest rate is 10%, using the present value method, which bid should be accepted