424. Calculate $\log _{a b c \ldots k} x$, given

$$
\log _{a} x, \log _{b} x, \ldots, \log _{k} x, x \neq 1
$$
Instruction. For problem 415,

\[
\begin{aligned}
\log _{a b c \ldots k} x= & \frac{1}{\log _{x}(a b c \ldots k)}=\frac{1}{\log _{x} a+\log _{x} b+\ldots+\log _{x} k}= \\
& =\frac{1}{\frac{1}{\log _{a} x}+\frac{1}{\log _{b} x}+\ldots+\frac{1}{\log _{k} x}}
\end{aligned}
\]