please and help to calculate ROI

For the current year, Cara Nguyen of the Hotel Division has been given a target ROI of 35% p.a. She has been told that she will receive a bonus of $15,000 if she meets this target. Cara is considering introducing a fully automated Central Reservation System (CRS) to enhance the efficiency of her hotel's booking system. The automation will cost $30,000 and is expected to have the following benefits over the next few years: Completely eliminate booking errors and reduce booking related administrative costs by $100 per month. Due to increased booking and customer handling efficiency, hotel revenue is expected to increase by $500 per month. Cara believes that the CRS system has a positive Net Present Value. REQUIRED: a) Comment on the use of ROI to evaluate and reward Cara Nguyen's performance. Your answer should include a discussion of : Its effectiveness in communicating each division's competitive advantage; ii) Two advantages of using ROI as a performance measure; iii) Two disadvantages of using ROI as a performance measure. b) After much consideration, Cara decided not to introduce the CRS system in the current year. Provide an explanation for Cara's decision, based on the information contained in the question. You must provide calculations to support your