Assume the cost of a robotic system is 151. The salary and other costs of workers replaced is 27, the saving for using the robot is $15 K. Depreciation value is $28 K, based on a 32.9% depreciation. The maintenance cost are 7, and new staffing cost are $32 K. What is the payback period? P= C / ((W+I+D) - (M + S).