To evaluate the expression \( \frac{s - t}{st + s} \) for \( s = 5 \) and \( t = 0 \), we will substitute the values into the expression.
First, calculate \( s - t \): \[ s - t = 5 - 0 = 5 \]
Next, calculate \( st + s \): \[ st + s = (5)(0) + 5 = 0 + 5 = 5 \]
Now we can substitute these values into the expression: \[ \frac{s - t}{st + s} = \frac{5}{5} \]
Simplifying the fraction: \[ \frac{5}{5} = 1 \]
Thus, the simplified result of the expression is: \[ \boxed{1} \]