The reflection of the plane $2\mathrm{x}-3\mathrm{y}+4\mathrm{z}-3=0$ in the plane $\mathrm{x}-\mathrm{y}+\mathrm{z}-3=0$ is the plane 

  we know that reflection of ${\mathrm{a}}^1\mathrm{x}+{\mathrm{b}}^1\mathrm{y}+{\mathrm{c}}^1\mathrm{z}+{\mathrm{d}}^1=0\text{ in the plane }\mathrm{ax}+\mathrm{by}+\mathrm{cz}+\mathrm{d}=0$ is given by
$\begin{array}{l}2\left({\mathrm{aa}}^1+{\mathrm{bb}}^1+{\mathrm{cc}}^1\right)(\mathrm{ax}+\mathrm{by}+\mathrm{cz}+\mathrm{d})\\ =\left({\mathrm{a}}^2+{\mathrm{b}}^2+{\mathrm{c}}^2\right)\left({\mathrm{a}}^1\mathrm{x}+{\mathrm{b}}^1\mathrm{y}+{\mathrm{c}}^1\mathrm{z}+{\mathrm{d}}^1\right)\end{array}$
 By using this formula we will get  required plane

$$\begin{gathered} where a^1=2,b^1=-3,c^1=4 ,d^1=-3 and a=1,b=-1,c=1,d=-3 \\ \Rightarrow 2\left(9\right)(x-y+z-3)=3(2x-3y+4z-3) \\ \Rightarrow 4x-3y+2z-15=0 \end{gathered}$$