To solve this problem we need the concepts about Bernoulli variables.
Then we define the two probabilities and states that we have
We have two individuals, Bill and Tom.
Let's consider:
for the 8/10 probability that Bill is first ranker.
For the probability that Tom is the first ranker (Or bill is third ranker)
Then,

Of 10 games played, Bill has won 8.
P(X=1) = 0.8