8.25 Three people, A, B, and C, are playing a game: There are three cards, each with a positive integer $p$, $q$, $r$ written on it, and $p<q<r$. After shuffling, the cards are distributed to the three people, one each, and marbles are given according to the number on each person's card. Then the cards are collected and reshuffled, but the marbles each person receives are kept by themselves. This process of shuffling, dealing, and giving marbles is repeated at least twice. It is known that at the end of the game, A, B, and C have 20, 10, and 9 marbles respectively, and B knows he received $r$ marbles the last time. Who got $q$ marbles in the first game?
[Solution] Let the number of game rounds be $n$, then
$$
n(p+q+r)=20+10+9=39 .
$$

Since $0<p<q<r$, we have $p+q+r \geqslant 6$. Also, since $n \geqslant 2$, we know that $n=3$ and $p+q+r=13$.

Given that player B gets $r$ marbles in the last round, and the total number of marbles he gets in 3 rounds is less than $\frac{1}{3}$ of the total number of marbles distributed, it follows that B gets $p$ marbles in the other two rounds. Therefore, we have
$$
p+p+r=10 .
$$

Since player C gets fewer marbles in total than B, he does not get $r$ marbles in any round. Since B gets $p$ marbles in the first round, C gets $q$ marbles in the first round.