\[\sqrt{\frac{36a^{4}}{25b^{2}c^{4}}} - \frac{c^{2}b}{6\sqrt{a^{2}}} =\]
\[= \frac{6{a^{2}}^{\backslash 6a}}{5bc^{2}} - \frac{c^{2}b^{\backslash 5bc^{2}}}{6a} =\]
\[= \frac{36a^{3} - 5b^{2}c^{4}}{30abc^{2}}.\]