13. Given that $(m-2)$ is a positive integer and it is also a factor of $3 m^{2}-2 m+10$. Find the sum of all such values of $m$.
13. Ans: 51 .
Since
$$
\frac{3 m^{2}-2 m+10}{m-2}=3 m+4+\frac{18}{m-2}
$$
is an integer. Thus $m-2$ is a factor of $18 . m-2=1,2,3,6,9,18$, thus $m=3,4,5,8,11,20$. The required sum is 51 .