Please help me to solve this problem. Thank you!

Imagine that you've just won the new University of Virginia MiniLottery, and have two options for the payment of your prize. The first is to receive three equal annual payments (the first coming immediately) of 7000 dollars apiece. The second is to immediately receive a single payment of 19900 dollars. If lottery Commissioner Sandridge claims that the two options are equivalent, what effective rate of interest is being assumed