How can I solve Adding Scientific Notation with numbers with decimals

Solution
[tex]\begin{gathered} 4.9\cdot10^{-5}+0.0005 \\ 0.000049+0.0005=0.000549 \\ \\ 0.000549=5.49\times10^{-4} \\ \end{gathered}[/tex]The final answer
[tex]5.49\times10^{-4}[/tex]