Question 697cd383

$x$	$f (x)$
$1$	$negative 64$
$2$	$0$
$3$	$64$

For the linear function $f$ , the table shows three values of $x$ and their corresponding values of $f (x)$ . Function $f$ is defined by $f (x) = a x + b$ , where $a$ and $b$ are constants. What is the value of $a - b$ ?

Algebra - Linear functions