It seems that you added all of the exponents. There are two different rules of exponents that you must apply here. First you must simplify $\displaystyle{{\left({{y}}^{{5}}\right)}}^{{2}}\usepackage{cmbright}\Huge\$ using the power rule: $\displaystyle{{\left({{x}}^{{a}}\right)}}^{{b}}={{x}}^{{{a}\cdot{b}}}\usepackage{cmbright}\Huge\$ . Then to complete the problem you must use the product rule: $\displaystyle{{x}}^{{a}}\cdot{{x}}^{{b}}={{x}}^{{{a}+{b}}}\usepackage{cmbright}\Huge\$ .