Answer
False
The true statement should be:
"If $x$ is $3$, then the value of $-3x - 9$ is $-18$."
Work Step by Step
To find out if this statement is true or false, we want to substitute $-3$ for $x$:
$$-3(-3) - 9 = -18$$
Multiply first, according to order of operations:
$$9 - 9 = -18$$
Subtract:
$$0 = -18$$
We see that the two sides of the equation are not equal; therefore, this statement is false.
In order to make this statement true, we can substitute $3$ for $x$:
$$-3(3) - 9 = -18$$
Let's check. Multiply first, according to order of operations:
$$-9 - 9 = -18$$
Let's subtract:
$$-18 = -18$$
When we substitute $3$ in for $x$, the two sides of the equation; therefore, $3$ is a solution of the equation, not $-3$.
