Step 1:

Equation of the given line $AB$ is

\( \large\frac{x-3}{1}=\frac{y-2}{-2}=\frac{z-5}{4}\)

If two lines are parallel then the ratio of their direction ratios are proportional.

Hence the direction ratios of the line parallel to AB is

$1k,-2k,4k$

Where $k$ is a constant.