A special six-sided die has its faces numbered 1 through 6 and has the property that rolling each number $x$ is $x$ times as likely as rolling a 1. For example, the probability of rolling a 5 is 5 times the probability of rolling a 1 , while the probability of rolling a 2 is 2 times the probability of rolling a 1. Robbie and Francine play a game where they each roll this die three times, and the total of their three rolls is their score. The winner is the player with the highest score; if the two players are tied, neither player wins. After two rolls each, Robbie has a score of 8 and Francine has a score of 10. The probability that Robbie will win can be written in lowest terms as $\frac{r}{400+s}$, where $r$ and $s$ are positive integers. What is value of $r+s$ ?
(A) 96
(B) 86
(C) 76
(D) 66
(E) 56