To simplify the expression \( 3^7 \cdot 3^{-9} \) using the properties of integer exponents, we can apply the property that states:
\[ a^m \cdot a^n = a^{m+n} \]
In this case, \(m = 7\) and \(n = -9\). Thus, we can combine the exponents:
\[ 3^7 \cdot 3^{-9} = 3^{7 + (-9)} = 3^{7 - 9} = 3^{-2} \]
Next, we rewrite \(3^{-2}\) with only positive exponents. The property for negative exponents states:
\[ a^{-n} = \frac{1}{a^n} \]
So, we have:
\[ 3^{-2} = \frac{1}{3^{2}} = \frac{1}{9} \]
Thus, the equivalent expression to \( 3^7 \cdot 3^{-9} \) with only positive exponents is:
\[ \frac{1}{9} \]
The final answer is:
\[ \frac{1}{9} \]