Answer
$(x+y)(5+a)$
Work Step by Step
Upon inspection, we find that $5$ is common to the first two terms of the expression while $a$ is common to the last two terms of the expression:
$5x+5y+ax+ay$
=$5(x+y)+a(x+y)$
Since $(x+y)$ is now common to the expression, we factor it out:
$5(x+y)+a(x+y)=(x+y)(5+a)$
The expression cannot be factored further.
