Answer: last option.
Step-by-step explanation:
According to the Product of powers property, you have:
[tex]a^n*a^m=a^{(n+m)}[/tex]
As you can see, when you can add the exponents when you have powers with equal base.
Then, [tex]6^5[/tex] and [tex]5^{-3}[/tex] do not have the same base, therefore, the exponents can't be added.
Therefore, Eli is incorrect, because he added the exponents even though the bases are not the same.
