* 4.2.73 Solve using augmented matrix methods. 4 Xy + 6X2 = 6 -6X1 - 9X2 = -9 Select the correct choice below and, if necessary, fill in the answer box to complete your choice. The O A. The unique solution is x, = and X2 =. (Simplify your answer.) O B. The system has infinitely many solutions. The solution is x, = and X2 = t. (Simplify your answer. Type an expression using t as the variable. Do not factor.) O C. There is no solution