please solve using Excel formulas

The B/C ratio for a flood control project along the Swanee River was calculated to be 1.4. If the benefits were $600,000 per year and the maintenance costs were $200,000 per year. Using Goal-Seek determine the initial cost of the project at an interest rate of 8% per year and a 50-year life. Hint: Set up problem to calculate the B/C with given data; using any number for the PW of initial cost