$\begin{aligned}
& \operatorname{fog}(x)=f(g(x)) \
& =f\left(\frac{2-3 x}{1-x}\right)=\frac{2\left(\frac{2-3 x}{1-x}\right)+3}{5\left(\frac{2-3 x}{1-x}\right)+2} \
& =\frac{4-6 x+3-3 x}{10-15 x+2-2 x}=\left(\frac{7-9 x}{12-17 x}\right) \
& \therefore\left[\begin{array}{c}
12-7 x \neq 0 \
x \neq \frac{12}{17}
\end{array}\right. \
& {\left[\begin{array}{l}
\operatorname{fog}(2)=\frac{7-9(2)}{12-17(2)}=\frac{-11}{-22}=\frac{1}{2} \
\operatorname{fog}(4)=\frac{7-9(4)}{12-17(4)}=\frac{-29}{-56}=\frac{29}{56}
\end{array}\right.} \
& \text { Range of fog : }[\alpha, \beta]=\left[\frac{1}{2}, \frac{29}{56}\right] \
& \therefore(\beta-\alpha)=\frac{29}{56}-\frac{1}{2}=\frac{29-28}{56}=\frac{1}{56} \
& \frac{1}{(\beta-\alpha)}=56
\end{aligned}$