If (a, b, c) is the image of the point (1,2,-3) in the line,

Line is $\frac{x+1}{2}=\frac{y-3}{-2}=\frac{z}{-1}=\lambda:$ Let point $R$ is

$(2 \lambda-1,-2 \lambda+3,-\lambda)$

Direction ratio of $\mathrm{PQ}=(2 \lambda-2,-2 \lambda+1,3-\lambda)$ $P Q$ is $\perp^{r}$ to line

$\Rightarrow 2(2 \lambda-2)-2(-2 \lambda+1)-1(3-\lambda)=0$

$4 \lambda-4+4 \lambda-2-3+\lambda=0$

$9 \lambda=9 \Rightarrow \lambda=1$

$\Rightarrow \quad$ Point $\mathrm{R}$ is $(1,1,-1)$

$\Rightarrow a+b+c=2$