Hi LUANDATO,

We're told that Team X won 40 percent of the 45 games it has played so far during this season. We're asked for the percent of all its games that Team X wins in total (there are no ties permissible).

To start, we know that of the first 45 games, 40% of them (18 games) were wins. To answer this question, we'll need information that helps to determine the number of ADDITIONAL games played and the number of ADDITIONAL wins.

1) Team X won 1/2 of its remaining games this season.

The information in Fact 1 essentially creates a 'weighted average', based on the total number of games that Fact 1 describes. In the prompt, we're told that 40% of the initial games were won; here, we're told that 50% of the remaining games are won. The smaller the number of additional games, the closer the average will be to 40%; the larger the number of additional games, the closer the average will be to 50%. Thus, there are a variety of different answers to the question.
Fact 1 is INSUFFICIENT

2) Team X played 64 games after June 1st.

Fact 2 gives us the overall TOTAL number of games (45 + 64 = 109 total games), but we don't know the number of additional wins in these 64 games.
Fact 2 is INSUFFICIENT

Combined, we know the total number of games played (109) and the total number of wins (18 + half of 64 = 50). Thus, the answer IS 50/109.
Combined, SUFFICIENT

Final Answer: C

GMAT assassins aren't born, they're made,
Rich