(1 point) You are given the four points in the plane A = (0, 7), B = (4, -3), C = (6, 8), and D = (9, -8). The graph of the function f(x) consists of the three line segments AB, BC and CD. Find the integral f(x) dx by interpreting the integral in terms of sums and/or differences of areas of elementary figures. f (x) dx =