there are (3x3=9) cases possible. in 3 cases there will be a tie. out of 6 cases left luis and brianna have equal chances of winning, so in 3 cases brianna will win and in other 3 luis will win. so the probability of luis winning the game is:
(favorable outcomes) / (total # of outcomes) = 3/9 = 1/3.
Answer: 1/3