Correct.

$\displaystyle{30}{{m}}^{{4}}={2}\cdot{3}\cdot{5}\cdot{m}\cdot{m}\cdot{m}\cdot{m}\usepackage{cmbright}\Huge\$

$\displaystyle{36}{{m}}^{{6}}={2}\cdot{2}\cdot{3}\cdot{3}\cdot{m}\cdot{m}\cdot{m}\cdot{m}\cdot{m}\cdot{m}\usepackage{cmbright}\Huge\$

GCF $\displaystyle={2}\cdot{3}\cdot{m}\cdot{m}\cdot{m}\cdot{m}={6}{{m}}^{{4}}\usepackage{cmbright}\Huge\$

The missing exponent is 4.