Answer
(a) $a \gt b$
(b) $a \lt b$
Work Step by Step
We can state the Trichotomy Property: For any two real numbers $a$ and $b$, exactly one of these statements is true: $a\gt b, ~~a = b, ~~a \lt b$
(a) $a = \frac{12}{-2} = -6$
$b = 4(-2) = -8$
$a \gt b$
(b) $a = 2^3 = 8$
$b = 3^2 = 9$
$a \lt b$