Final answer:
The graph of g(x) is obtained by shifting down the graph of f(x) by 13 units due to the difference in their y-intercepts.
Step-by-step explanation:
The graph of g(x) is obtained by shifting down the graph of f(x) by 13 units. This is because the only difference between the two functions f(x) = 7x + 9 and g(x) = 7x - 4 is in their y-intercepts; f(x) intercepts the y-axis at 9, while g(x) intercepts it at -4. This change in the y-intercept signifies a vertical shift of the graph downwards by the difference between the y-intercepts, which is 9 - (-4) = 13 units.