Consider the following linear system. a - 2b + d = 4 -a + + b - c - 8d = 1 Create the augmented matrix of this system. 1 -2 0 4 -1 1 -1 -8 1 Convert the system into one that exhibits the triangular structure where the ? represent numerical values. 1 -2 0 1 4 0 7 -5 Write the linear system corresponding to the simplified matrix above, then solve the linear system. (If your answer is dependent, use the parameters s and t as necessary. If there is no solution, enter NO SOLUTION.) [a, b, c, d] = x