2. (Suzhou City) The roots of the equation $x^{2}-a x+b=0$ are $\alpha, \beta$ and the roots of $3 x^{2}-b x+c=0$ are $\gamma, \delta$. Let $M$ $=\{\alpha, \beta, \gamma, \delta\}, S=\{x \mid x=u+v, u \neq v, u$, $v \in M\}, P=\{x \mid x=u v, u \neq v, u, v \in M\}$. It is known that $S=\{5,7,8,9,10,12\}, P=\{6,10,14$,
$15,21,35\}$, then $a=$ $\qquad$ ,$b=$ $\qquad$ ,$c=$ $\qquad$
\[
\begin{aligned} 2, a & =7, b=10, \\ c & =21 .\end{aligned}
\]