The reflection of the complex number $\frac{2+i}{3-i}$ in the straight line $(1+i)z=(1-i)\overline{z}$, is

$\frac{2+\mathrm{i}}{3-\mathrm{i}}\equiv \mathrm{P}\left(\frac{1}{2},\frac{1}{2}\right)$

Also, $(1+i)z=(1-i)\overline{z}\Rightarrow x+y=0$

So, reflection of $\mathrm{P}\left(\frac{1}{2},\frac{1}{2}\right)$in the line $\mathrm{x}+\mathrm{y}=0,$ is $\mathrm{Q}\left(\frac{-1}{2},\frac{-1}{2}\right)=\frac{2+\mathrm{i}}{-3+\mathrm{i}}$