Answer
The sum of the measurements of $6128\text{km}$$,1520\text{km}$, $16.28\text{km}$ and $225\text{km}$ is $7890\text{km}$.
Work Step by Step
All the measurements are in the same unit of $\text{kms}$.
Therefore, the sum of the measurements is,
$\begin{align}
& 6128+1520+16.28+225=7889.28\text{km} \\
& 6128+1520+16.28+225\approx 7890\text{km} \\
\end{align}$
