Correct. You subtracted $\displaystyle{17}{{q}}^{{2}}\usepackage{cmbright}\Huge\$ from $\displaystyle{39}{{q}}^{{2}}\usepackage{cmbright}\Huge\$ , which yields $\displaystyle{22}{{q}}^{{2}}\usepackage{cmbright}\Huge\$ . Your answer reflects that the $\displaystyle{{y}}^{{3}}{{q}}^{{2}}\usepackage{cmbright}\Huge\$ terms cancelled.