$3\mathrm{.}40$ A build$-$to$-$operate $($BTO$)$ company signed a contract to operate Alamosa County industrial wastewater treatment plants for the next $20$ years. The contract will pay the company $$2\mathrm{.}5$ million now and amounts increasing by $$200,000$ each year through year $20.$ At an interest rate of $10\%$ per year, what is the present worth now? Solve using $($a$)$ tabulated factors, and $($b$)$ a spreadsheet. Draw the cashflow diagram