Answer
-1
Work Step by Step
A natural logarithm is a logarithm to base $e$. As shown on page 582, when a natural logarithm is written in the form $ln (x)$, this is equivalent to the expression $log_{e}x$.
Therefore, $ln \frac{1}{e}=log_{e}\frac{1}{e}=-1$. We know this, because $(e)^{-1}=\frac{1}{e^{1}}=\frac{1}{e}$.
