For example, I can solve: $x \log_2(x) = y$
$x \log_2(x) = x \log_e(x) / \log_e(2) = e^{\log_e(x)} \log_e(x) / \log_e(2)$
$e^{\log_e(x)} \log_e(x) = y\log_e(2)$
$e^{W(z)} W(z) = z$, where W(z) is the Lambert W-function
$log_e(x) = W(y\log_e(2))$
$x = e^{W(y\log_e(2))}$
But how to (find $x$) solve: $\frac{x}{\log_2(x)} = y$
Answer:
$$\displaystyle\begin{array}$x&=& \frac{1}{e^{W(ln(\frac{1}{2})^{1/y})}} = \frac{1}{e^{W(−ln(2)/y)}} \end{array}$$