what is 2.5 cm if it equals 0.1 km

What is 2.5 cm if 1cm equals 0.1 km ?

$$\small{\text{
$
\begin{array}{rcl}
1\ \mathrm{cm} & \widehat{=} & 0.1 \ \mathrm{km} \\
2.5\ \mathrm{cm} & \widehat{=} & x \ \mathrm{km}
\end{array}
$
}}\\\\
\small{\text{
$\dfrac{1}{2.5} = \dfrac{0.1}{x} $}} \\\\
\small{\text{
$\dfrac{2.5}{1} = \dfrac{x}{0.1} $}} \\\\
\small{\text{
$ x=0.1\cdot \dfrac{2.5}{1} $}} \\\\
\small{\text{
$ x=0.25\ \mathrm{km} $}} \\\\$$