6. In an opaque bag, there are several red, yellow, and blue glass balls that are identical except for their color. Among them, there are 6 red glass balls and 9 yellow glass balls. It is known that the probability of randomly drawing 1 blue glass ball from the bag is $\frac{2}{5}$. Then, the probability of randomly drawing 1 red glass ball is . $\qquad$
二、6. $\frac{6}{25}$.
Let the number of blue glass balls in the bag be $x$.
Then $\frac{x}{15+x}=\frac{2}{5} \Rightarrow x=10$.
Therefore, the required probability is $\frac{6}{6+9+10}=\frac{6}{25}$.