Please provide the formula as well

Required: 1. Determine the payback period of the investment. 2. Would the payback period be affected if the cash inflow in the last year were several times as large? Complete this question by entering your answers in the tabs below. Determine the payback period of the investment. (Round your answer to 1 decimal place.) Would the payback period be affected if the cash inflow in the last year were several times as large