2009 AIME II Problem 8

Dave rolls a fair six-sided die until a six appears for the first time. Independently, Linda rolls a fair six-sided die
until a six appears for the first time. Let m and n be relatively prime positive
integers such that \frac{m}{n} is the probability that the number of times Dave rolls his die is equal to or within one of the number
of times Linda rolls her die. Find m+n.