The direction cosines of the normal to the plane containing the lines having direction ratios 1, 2, 1 and 4, 5, -3 are

$b_1\times b_2=\left|\begin{array}{l}ijk\\ 121\\ 45-3\end{array}\right|$
$=-11i+7j-3k$
$\therefore$Direction cosines of normal to the plane
$\begin{array}{l}=\frac{-11}{\sqrt{{(-11)}^2+7^2+{(-3)}^2}},\frac{7}{\sqrt{{(-11)}^2+7^2+{(-3)}^2}}\\ \frac{-3}{\sqrt{{(-11)}^2+7^2+{(-3)}^2}}=\frac{-11}{\sqrt{179}},\frac{7}{\sqrt{179}},\frac{-3}{\sqrt{179}}\end{array}$