A = 2 1.....x = x_1.......b = 3

......4 3..........x_2............4

[A][x] = [b]

row times column ...

2x_1 + 1x_2 = 3

4x_1 + 3x_2 = 4

x_2 = -2

substitute x_2 = -2 in either equation ...

2x_1 + (-2) = 3

2x_1 = 5

x_1 = 5/2

4x_1 + 3(-2) = 4

4x_1 = 10

x_1 = 5/2