Multiply the expression on the left, finding the product in simplest form. Then supply the missing numerator.

$\displaystyle\frac{{2}}{{{3}{{x}}^{{2}}}}\cdot\frac{{{12}{{x}}^{{3}}}}{{14}}=\frac{?}{{7}}\usepackage{cmbright}\Huge\$

The missing numerator is _____.