On a coordinate plane, 2 triangles are shown. The first triangle has points F prime (1, 5), E prime (negative 1, 1), and D prime (negative 4, 2). The second triangle has points E (1, negative 1), D (2, negative 4), and F (5, 1). Complete the mapping of the vertices of ΔDEF. D(2, –4) → D' E(1, –1) → E' F(5, 1) → F' What is the rule that describes a reflection across the line y = x? rx = y(x, y) →