Answer
$5(3+x)$
Work Step by Step
RECALL:
The commutative property of addition states that for any real numbers $a$ and $b$,
$a+b=b+a$
If you apply the commutative property of addition to $x+3$. you'd get $3+x$ as an equivalent expression.
Thus, the given algebraic expression is equivalent to:
$5(3+x)$