For the answer given, You win the lottery today, and receive payment 1 one year from today, payment 2 two years from today.... Up to the 20th payment. Each payment is equal in value, so;

edit; it is a bit confusing, as if I won the lottery, I would want to receive the first payment now, not have to sit and wait for a year after winning the big jackpot! But the question doesn't specify when you receive the first payment..