Using excel please. Find the present worth for each using excel formulas, and decide which option is the best economically

Charlie's Truck Repair and Service has a new contract that requires him to purchase and maintain new equipment for work on 18-wheeler trucks and heavy road equipment. Two separate vendors have made quotes and estimates for Charlie. Use the estimates and a 6% per year return requirement to find the better economic option. One problem is that Charlie does not currently know if the contract will last for 5, 8, or 10 years. He needs a recommendation for all three time periods