Saturn is:
[tex]8.7\times10^8[/tex]and earth is:
[tex]9.1\times10^7[/tex]so we can made the cienthific notation equal so:
[tex]8.7\times10^8=87\times10^7[/tex]so now we can rest the difference so:
[tex]\begin{gathered} 87\times10^7-9.1\times10^7 \\ =77.9\times10^7 \end{gathered}[/tex]