To apply the Property of Negative Integer Exponents, we can use the rule that states \( a^{-n} = \frac{1}{a^n} \).
Let's start with the expression:
\[ 7^{-3} \cdot 7^{-5} \]
According to the properties of exponents, when multiplying powers with the same base, we can add the exponents:
\[ 7^{-3} \cdot 7^{-5} = 7^{-3 + (-5)} = 7^{-8} \]
Now, we apply the property of negative exponents:
\[ 7^{-8} = \frac{1}{7^8} \]
Thus, the expression \( 7^{-3} \cdot 7^{-5} \) can be rewritten with positive exponents as:
\[ \frac{1}{7^8} \]
So, the equivalent expression with positive exponents only is:
\[ \frac{1}{7^8} \]