A firm is considering which of two mechanical devices to install to reduce costs in a particular situation. Both devices cost $1000 and have useful lives of five years and no salvage value. Device A can be expected to result in $300 savings annually. Device Brandon will provide cost saving of $400 the first year but will decline by $50 annually, making the second year saving to $350 and third year savings $300 and so forth. With interest at 7% per year, which device should the the firm purchaseed?