Billie and his friends are playing a board game where you go froward on the board if you throw an even number on a pair of dice, and backwards if you throw an odd number on a pair of dice. Billie's first throw is a 12, and his second throw is a 9, his third throw is an 8, and his fourth throw is a 4. How far has Billie gone from the start of the board game? (If you throw odd numbers that would take you off the board, you stay at the starting point.) Explain how you got your answer.