Final answer:
The graph of the function f(x) described in the question is a horizontal line from x=0 to x=20.
Step-by-step explanation:
The question asks for the graph of a function f(x) which has opposite expressions. Based on the information given, we know that the function f(x) is a horizontal line between x = 0 and x = 20, inclusive. Since the function is a horizontal line, it means that the value of f(x) is constant for all x within that range. Therefore, the graph of f(x) would be a straight, horizontal line that spans from x = 0 to x = 20.