A new project is under evaluation. The project needs investment in a machine costs $34,500 with four-year life. Sales are projected to be 2,300 unit per year; Price per unit will be $20, variable cost per unit is $ 10; fixed cost is $17,500. Discount rate is 15%. You want to find out projected information for best-worse scenarios. Assume prediction are accurate to within +/- 12 percent. What is variable cost per unit under worst case? (round and format your answer to ONE DECIMAL, enter only numeric numbers, without any text such as "$", or space; for example: 15.9)