(1 point) Rewrite each system of equations in the form Ax = b. 7a + 9b = 9 5a + 5b 2 7 is equivalent to Ax = b if The system { A = , 2a =2 2a + 8b = 3 is equivalent to Ax = b if The system { A: , x: ,and \f9a + 8b + 9c = 6 The system 9a + 5b +9c = 8 is equivalent to Ax = b if 2b = 7 A = X = and b =