[tex]7^0=1[/tex].
So here, it seems that you know for any nonzero real number b, the zero exponent rule states that [tex]b^0 = 1[/tex]. Now, [tex]b[/tex] is just a general form for any base. This rule is always true for any nonzero number, including 7, for the problem you are solving.
For instance, I'm sure you would agree that [tex] \dfrac{3}{3} = 1[/tex] (identity or inverse rule). Now, isn't this the same thing as writing [tex] \dfrac{3^1}{3^1} = 1[/tex]? By the quotient rule, you can similarly write [tex]3^{1-1}=3^0=1[/tex].
