Correct. The equation $\displaystyle\frac{{1}}{{p}}+\frac{{1}}{{{3}{p}}}=\frac{{1}}{{4}}\usepackage{cmbright}\Huge\$ represents the rate of the fast pipe $\displaystyle{\left(\frac{{1}}{{p}}\right)}\usepackage{cmbright}\Huge\$ , the slow pipe $\displaystyle{\left(\frac{{1}}{{{3}{p}}}\right)}\usepackage{cmbright}\Huge\$ , and the rate at which the pool was filled $\displaystyle{\left(\frac{{1}}{{4}}\right)}\usepackage{cmbright}\Huge\$ .