A lаbоrаtоry prоjects thаt a new test line will generate $[a] in annual gain (net profit). The investment required to launch the test line costs $[b]. Using the payback-period interpretation of ROI, how many years will it take to recover the cost of the investment?Formula: Payback Period = Cost of Investment ÷ Annual Net Profit(Round to one decimal place. Enter the number only — no units.)