Although $\displaystyle\frac{{9}}{{15}}\usepackage{cmbright}\Huge\$ is an equivalent fraction to $\displaystyle\frac{{72}}{{120}}\usepackage{cmbright}\Huge\$ , the numerator and denominator have a common factor, 3, so this fraction cannot be in lowest terms. The correct answer is: $\displaystyle\frac{{3}}{{5}}\usepackage{cmbright}\Huge\$