Answer
44 Degrees Kelvin
Work Step by Step
We know the following equation, which is equation 16.9:
$P=e\sigma AT^4$
Since it is a black body, we know that e is equal to one. Thus, we find:
$T = (\frac{P}{\sigma A })^.25 = (\frac{.876}{4\times5.67\times10^{-8} })^.25=44.33 K$