The most points a player can accumulate over 54 games is 324. In each game, a player can score a 1,2,3,4,5 or 6 points. There's a total of 15 players in the league.
The 5 highest scoring players make the playoffs.
How do I calculate when a player is mathematically eliminated, meaning they can no longer score enough points to make the playoffs (5th place)
I'm not sure this is the right area to put this question...
Let $x$ be a given player's score, let $y$ be the score of player who currently has the fifth highest score, and let $n$ be the number of games left. We should look at the scenario where the given player does as well as possible for the rest of the games and the player with the high score does as poorly as possible. In this scenario we need to have $x + 6n \geq y + 1n$ for the given player to still have a shot at winning, which can be cleaned up to be $$ x + 5n \geq y $$