Correct. $\displaystyle-{12}{{x}}^{{7}}\usepackage{cmbright}\Huge\$ must be distributed to all three terms in the parentheses. $\displaystyle-{12}{{x}}^{{7}}{\left({5}{{x}}^{{5}}+{6}{x}-{9}{{x}}^{{3}}\right)}=-{12}{{x}}^{{7}}{\left({5}{{x}}^{{5}}\right)}+{\left(-{12}{{x}}^{{7}}\right)}{\left({6}{x}\right)}-{\left(-{12}{{x}}^{{7}}\right)}{\left({9}{{x}}^{{3}}\right)}=-{60}{{x}}^{{{12}}}-{72}{{x}}^{{8}}+{108}{{x}}^{{{10}}}\usepackage{cmbright}\Huge\$ .