Question

Item 8 factor −5 out of −10a−25.

Answer 1

To factor a number out of an expression means to divide each term of the expression by that number.

So, if you want to factor $a$ from the expression $x+y+z$, you'll write it as

$a\left(\dfrac{x}{a}+\dfrac{y}{a}+\dfrac{z}{a}\right)$

So, in your case, when you divide both terms by -5 you get

$-10a \div (-5) = 2a,\quad -25\div (-5) = 5$

So, the expression becomes

$-10a-25 = -5(2a+5)$