You have a dartboard that is split in half. If you hit the left half, you get 2 points; if you hit the right half, you get 3 points. You have an 80% chance of hitting the dartboard on any given throw and, if you hit the board, a 70% chance of hitting the side you are aiming for (and a 30% chance of hitting the other side). With an unlimited number of throws, what is the probability that you achieve a score of exactly 7?