4. For each one of the following systems of linear equations: 20 30 10 = 8x1 + 3.02 = 12.62 +6.03 = x1 + 1083 2x1 + x2 +5.23 = 1 2.21 + 2.02 + 2x3 = 1 4x1 + x2 = 2 21 + x2 - x3 = -3 621 + 2.02 +2.13 = 2 -301 + 4.x2 + x3 = 1 (a) Use Gaussian Elimination (2.0) with backward substitution to find the solution. Show the resulting matrices after each one of the matrix row operations. (b) Use Cramer's Rule to solve them. Compute the determinants using minors