Answer
$-20^{\circ}C$.
Work Step by Step
The given formula is
$\Rightarrow C=\frac{5}{9}(F-32)$
Substitute $F=-4^{\circ}$.
$\Rightarrow C=\frac{5}{9}(-4-32)$
Simplify.
$\Rightarrow C=\frac{5}{9}(-36)$
$\Rightarrow C=-20$
Hence, the temperature is $-20^{\circ}C$.
