If you want to subtract them in scientific notation, first you need to make both exponents equal. One of them is raised to 5 and the other is raised to 4.
[tex]7.09[/tex] x [tex]10^{5}[/tex]
[tex]6.10[/tex] x [tex]10^{4}[/tex]
To make the first one raised to four, all you need to do is move the decimal to the right. The new notation will then be:
[tex]70.9[/tex] x [tex]10^{4}[/tex]
Now all you need to do is line up the decimals like you would normally and then subtract. Also copy the [tex]10^{4}[/tex]
[tex]70.9[/tex] x [tex]10^{4}[/tex]
-[tex]6.10[/tex] x [tex]10^{4}[/tex]
=
[tex]64.8[/tex] x [tex]10^{4}[/tex]
Then we to make it in standard form, just move the decimal to the left and add 1 to the exponent.
[tex]6.48[/tex] x [tex]10^{5}[/tex]
