#### Answer

$5(x-3z)$

#### Work Step by Step

The distributive property holds that $a(b-c)=ab-ac$, for real numbers a, b, and c.
In this example, we are given $5x-15z$. Therefore, we know that $ab-ac=5x-15z$.
We must factor out $a$ in order to find $a(b-c)$. 5 is the greatest common factor of the terms $ab$ and $ac$. Therefore, $a=5$, $b=x$, and $c=3z$.
So, $a(b-c)=5(x-3z)$