Incorrect. To simplify this expression, multiply the factors under the radical signs:

$\displaystyle{2}\sqrt{{{6}{{x}}^{{7}}}}\cdot{5}\sqrt{{{15}{{x}}^{{2}}}}={10}\sqrt{{{6}{{x}}^{{7}}\cdot{15}{{x}}^{{2}}}}={10}\sqrt{{{90}{{x}}^{{9}}}}\usepackage{cmbright}\Huge\$

Identify perfect square factors and rewrite as a product. Simplify using: $\displaystyle\sqrt{{{{a}}^{{2}}}}={a}\usepackage{cmbright}\Huge\$

The correct answer is 30.