Answer
Factor $2$ out of the second column and factor $3$ out of the third column.
Work Step by Step
$$
\left|\begin{array}{rrr}{1} & {2} & {3} \\ {4} & {-8} & {6} \\ {5} & {4} & {12}\end{array}\right|=6\left|\begin{array}{rrr}{1} & {1} & {1} \\ {4} & {-4} & {2} \\ {5} & {2} & {4}\end{array}\right|.
$$
Factor $2$ out of the second column and factor $3$ out of the third column.