Answer
$x=5$
Work Step by Step
$f(x)=15-3x$
Since we are solving for all the real values of $x$ when $f(x) = 0$, set the function $f(x)=15-3x$ equal to zero and we get the following equation:
$15-3x=0$
Now subtract 15 from both sides of the equation so that all of the constants are on the right side of the equation and all of the $x$ terms are on the left side.
$15-3x-15=0-15$
$-3x=-15$
Once all of the constants are on the right and all the $x$ terms are on the left, solve for $x$ by dividing both sides by $-3$.
$\frac{-3x}{-3}=\frac{-15}{-3}$
$x=5$
