A soccer team has won $60 \%$ of the 45 games already played. What is the minimum number of games this team still needs to win to achieve a $75 \%$ win rate?
The team has won $60 \%$ of the 45 matches already played, that is, $45 \times \frac{60}{100}=27$ matches. If the team wins $n$ more matches, the percentage of matches won will be

$$
\frac{\text{number of matches won}}{\text{number of matches played}}=\frac{27+n}{45+n}=75 \%=\frac{75}{100}=\frac{3}{4}
$$

Therefore, $4 \times(27+n)=3 \times(45+n)$, which results in $n=27$ as the minimum number of matches the team still needs to win to achieve $75 \%$ of victories.