You correctly found the least common denominator. However, you probably made a mistake when rewriting the first fraction, replacing $\displaystyle{\left({3}{x}+{1}\right)}{\left({x}+{9}\right)}\usepackage{cmbright}\Huge\$ with $\displaystyle{3}{{x}}^{{2}}+{9}\usepackage{cmbright}\Huge\$ . Remember to use FOIL when multiplying binomials. The correct answer is: $\displaystyle\frac{{{3}{{x}}^{{2}}+{29}{x}}}{{{{x}}^{{2}}+{6}{x}-{27}}}\usepackage{cmbright}\Huge\$