\[\frac{2}{y} = \frac{3}{x} - \frac{4}{z}\]
\[\frac{3}{x} = \frac{2}{y} + \frac{4}{z}\]
\[\frac{3}{x} = \frac{2z + 4y}{\text{yz}}\]
\[x = 3\ :\frac{2z + 4y}{\text{yz}}\]
\[x = \frac{2z + 4y}{3yz}.\]