Correct. Multiplying both sides of the equation by $\displaystyle{5}{\left({x}+{3}\right)}\usepackage{cmbright}\Huge\$ , he finds $\displaystyle{5}{\left({x}+{3}\right)}\cdot{\left(\frac{{x}}{{{x}+{3}}}\right)}+{5}{\left({x}+{3}\right)}\cdot{\left(\frac{{3}}{{5}}\right)}={5}{\left({x}+{3}\right)}\cdot\frac{{{11}{x}+{3}}}{{{5}{\left({x}+{3}\right)}}}\usepackage{cmbright}\Huge\$ , so $\displaystyle{5}{\left({x}\right)}+{3}{\left({x}+{3}\right)}={11}{x}+{3}\usepackage{cmbright}\Huge\$ .