Step by step solutions please. A table form with formulas in brackets would be appreciated. NO EXCEL SNAPSHOTS PLEASE

The business plan for KnowIt, LLC, a start-up company that manufactures portable multigas detectors, showed equivalent annual cash flows of $400,000 for the first 5 years. If the cash flow in year 1 was $316,000 and the constant increase thereafter was $50,000 per year, what interest rate was used in the calculation?