Final answer:
The question deals with a horizontal line function f(x) which has neither a minimum nor a maximum value since its output is constant. The vertex can be any point on this line with the constant y-value being the value of the function.
Step-by-step explanation:
The question provided deals with the function f(x) which is a horizontal line, indicating that the output of the function does not change regardless of the input x, as long as it is within the domain of 0 ≤ x ≤ 20. Since the function is a horizontal line, the vertex is any point along this line and there is neither a minimum nor maximum value because the function's value is constant. The value at the vertex is the constant value of the function across the entire domain.