To evaluate the expression \(10z + 5\) when \(z = 5\), we substitute \(5\) for \(z\) in the expression.
Starting with the expression:
\[ 10z + 5 \]
Substituting \(z = 5\):
\[ 10(5) + 5 \]
Now, we calculate \(10(5)\):
\[ 10 \times 5 = 50 \]
Now, we add \(5\) to this result:
\[ 50 + 5 = 55 \]
Thus, the value of the expression \(10z + 5\) when \(z = 5\) is
\[ \boxed{55} \]