To simplify the expression \( w^{z} \cdot w^{15} \), we can use the property of exponents that states when multiplying like bases, we add the exponents. Therefore, the expression simplifies to \( w^{z + 15} \).
Step 1: Identify the Expression
We start with the expression \( w^{z} \cdot w^{15} \).
Step 2: Apply the Property of Exponents
Using the property of exponents that states \( a^{m} \cdot a^{n} = a^{m+n} \), we can combine the exponents of the like bases. Thus, we have:
\[
w^{z} \cdot w^{15} = w^{z + 15}
\]
Final Answer
The simplified expression is \(\boxed{w^{z + 15}}\).