Answer
$-10^oF=-22.33^oC.$
Work Step by Step
To change from degrees Fahrenheit to degrees Celsius, we use the formula
$$C=\frac{5}{9}(F-32^o)=\frac{5}{9}(-10^o-32^o)=\frac{5}{9}\times (-42)=-23.33^o$$
that is $-10^oF=-22.33^oC.$
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