The distance between the cities is $\displaystyle\frac{{{920},{000}\ \text{ meters}}}{{1}}\cdot\frac{{{1}\ \text{ kilometer}}}{{{1},{000}\ \text{ meters}}}\usepackage{cmbright}\Huge\$ or 920 kilometers.

$\displaystyle\frac{{{920}\ \text{ km}}}{{n}}=\frac{{{230}\ \text{ km}}}{{{1}\ \text{ hour}}}\usepackage{cmbright}\Huge\$

$\displaystyle{n}=\frac{{920}}{{230}}={4}\usepackage{cmbright}\Huge\$