To apply the property of negative integer exponents, we can use the rule that states \( a^{-n} = \frac{1}{a^n} \).
For the expression \( 7^{-3} \cdot 7^{-5} \), we first combine the exponents since they have the same base. The property for multiplying expressions with the same base states:
\[ a^m \cdot a^n = a^{m+n} \]
Applying this to our expression:
\[ 7^{-3} \cdot 7^{-5} = 7^{-3 + (-5)} = 7^{-8} \]
Now, to express \( 7^{-8} \) with positive exponents, we use the negative exponent rule:
\[ 7^{-8} = \frac{1}{7^8} \]
Thus, the expression \( 7^{-3} \cdot 7^{-5} \) with positive exponents only is:
\[ \frac{1}{7^8} \]