The graph plots four equations, a, b, c, and d: line a joins ordered pair negative 6, 16 and 9, negative 4. line b joins ordered pair negative 2, 20 and 8, 0. line c joins ordered pair negative 7, negative 6 and 6, 20. line d joins ordered pair 7, 20 and 0, negative 7. which pair of equations has (4, 8) as its solution? equation a and equation c equation b and equation c equation c and equation d equation b and equation d