To find \( k(12) \) given the information about the inverse function \( k^{-1}(x) \), we can use the properties of inverse functions.
- We know that if \( k^{-1}(a) = b \), then it follows that \( k(b) = a \).
Given the provided information:
- \( k^{-1}(12) = 115 \) implies that \( k(115) = 12 \).
- \( k^{-1}(15) = 12 \) implies that \( k(12) = 15 \).
Now, based on this second conclusion:
\[ k(12) = 15. \]
Thus, the value of \( k(12) \) is 15.