Seattle Mariners First-Place Elimination Scenario
Seattle must win 2 more games (84 total) to avoid elimination from first place.
Here are the final standings in a scenario in which Seattle finishes in first place with 84 wins:

Team             W	L	PCT	GB
Seattle          84	78	0.519	0.00
Houston          84	78	0.519	0.00
Texas            83	79	0.512	1.00
Oakland          76	86	0.469	8.00
Los Angeles      75	87	0.463	9.00

Tie breakers
Seattle wins the series with Houston 7 games to 6

To construct the scenario, we start with the current standings in the division:
Team             W	L	GL	PCT	GB
Seattle          82	68	12	0.547	0.0
Houston          82	69	11	0.543	0.5
Texas            79	72	11	0.523	3.5
Oakland          70	80	12	0.467	12.0
Los Angeles      69	81	12	0.460	13.0

Next, we show how the remaining series of games plays out in the scenario:

Houston currently has 6 win(s) against Los Angeles and 4 loss(es).
Houston wins 1 additional game(s) against Los Angeles and loses 2.
Houston wins the series 7 games to 6.
Houston wins 0 additional game(s) against teams outside the division and loses 0.

Houston currently has 4 win(s) against Oakland and 6 loss(es).
Houston wins 0 additional game(s) against Oakland and loses 3.
Houston loses the series 4 games to 9.
Houston wins 0 additional game(s) against teams outside the division and loses 0.

Houston currently has 5 win(s) against Seattle and 5 loss(es).
Houston wins 1 additional game(s) against Seattle and loses 2.
Houston loses the series 6 games to 7.
Houston wins 0 additional game(s) against teams outside the division and loses 0.

Houston currently has 5 win(s) against Texas and 6 loss(es).
Houston wins 0 additional game(s) against Texas and loses 2.
Houston loses the series 5 games to 8.
Houston wins 0 additional game(s) against teams outside the division and loses 0.

Los Angeles currently has 9 win(s) against Oakland and 4 loss(es).
Los Angeles and Oakland have no remaining games.
Los Angeles wins the series 9 games to 4.
Los Angeles wins 4 additional game(s) against teams outside the division and loses 5.

Los Angeles currently has 4 win(s) against Seattle and 9 loss(es).
Los Angeles and Seattle have no remaining games.
Los Angeles loses the series 4 games to 9.
Los Angeles wins 4 additional game(s) against teams outside the division and loses 5.

Los Angeles currently has 5 win(s) against Texas and 8 loss(es).
Los Angeles and Texas have no remaining games.
Los Angeles loses the series 5 games to 8.
Los Angeles wins 4 additional game(s) against teams outside the division and loses 5.

Oakland currently has 6 win(s) against Seattle and 7 loss(es).
Oakland and Seattle have no remaining games.
Oakland loses the series 6 games to 7.
Oakland wins 3 additional game(s) against teams outside the division and loses 6.

Oakland currently has 5 win(s) against Texas and 8 loss(es).
Oakland and Texas have no remaining games.
Oakland loses the series 5 games to 8.
Oakland wins 3 additional game(s) against teams outside the division and loses 6.

Seattle currently has 10 win(s) against Texas and 3 loss(es).
Seattle and Texas have no remaining games.
Seattle wins the series 10 games to 3.
Seattle wins 0 additional game(s) against teams outside the division and loses 9.

# Seattle Mariners' magic number
# Seattle's magic number
# Mariners' magic number
# MLB Playoff Race