6. (10 points) A team currently has a win rate of $45 \%$. If they win 6 out of the next 8 games, their win rate will increase to 50\%. How many games has this team won so far? $\qquad$
【Solution】Solution: Assume that $x$ matches have been played, then
$$
\begin{array}{c}
(x+8) \times 50 \% =45 \% x+6 \\
0.5 x+4=0.45 x+6 \\
0.05 x=2 \\
x=40 ; \\
45 \% x=40 \times 45 \%=18 \text { (matches) }
\end{array}
$$

Answer: The team has now won 18 matches. Therefore, the answer is: 18.