Problem 1. (35 points) Find net annual worth for the following cash flows at 6% interest: Year 1 2 3 4 5 6 Cash flow $400 500 600 700 800-2500 Either use manual calculations with interest tables to find equivalent uniform annual benefits for positive cash flows for 6 years and equivalent uniform annual costs for 6 years for negative cash flow, and determine net annual worth; Or use Excel financial formulas to determine net annual worth for 6 years