Answer
$-50^{o}$ C
Work Step by Step
In order to convert Fahrenheit to Celsius, we use the formula:
$C=\displaystyle \frac{5}{9}(F-32)$
We plug in $-58$ for $F$:
$C=\displaystyle \frac{5}{9}(-58-32)$
$=\frac{5}{9}(-90)$
$=5*-10$
$=-50^{o}$ C