Answer
$(x-3)(y+9)$
Work Step by Step
Upon inspection, we find that $y$ is common to the first two terms of the expression while $9$ is common to the last two terms of the expression:
$xy-3y+9x-27$
=$y(x-3)+9(x-3)$
Since $(x-3)$ is now common to the entire expression, we factor it out:
$y(x-3)+9(x-3)=(x-3)(y+9)$
The expression cannot be factorize further.
