You may not have converted correctly from meters to kilometers. $\displaystyle\frac{{{280},{000}\ \text{ meters}}}{{1}}\cdot\frac{{{1}\ \text{ kilometer}}}{{{1},{000}\ \text{ meters}}}={280}\ \text{ kilometers}\usepackage{cmbright}\Huge\$ . The correct answer is $\displaystyle{3}\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$ hours.