You are tasked to justify the purchase of a robot that would cost $100,000 as a fixed price, plus an additional 15% annual maintenance. this robot will replace 4 workers that work an 8-hour shift every day in a 5-day week. if the total salary of each worker is $40,000, and given the following assumptions, calculate how many weeks it will take to fulfill the roi (return on investment): a) robot will work 3 shifts every day. b) robot's doesn't have a downtime but its maintenance cost is $15,000 per year which is charged annually. c) each worker will have 15 days of vacation and only 4 days of national holidays.