So for my economic class there's a problem about a wind mill farm that needs to make 2.1 million in…

So for my economic class there’s a problem about a wind mill farm that needs to make 2.1 million in electricity sales to pay back a loan, and the project produces 14,000,000 kWh per year. It sells each kWh at .15, now the question says that if the production fell short 10% how long would it take to pay off the full wind farm, in which the full wind farm costs 15,750,000?