### Pedagogical Fourier Motzkin

I want to decompose Fourier-Motzkin algorithm for educational reasons. Suppose I have

```
z_1=solve(4*x_2<=100,x_2)[0][0]
z_2=solve(-35*x_2<=-3,x_2)[0][0]
z_3=solve(12*x_2 <= 72,x_2)[0][0]
z_4=solve(1-1*x_2 <= 40,x_2)[0][0]
show(z_1,", ",z_2,", ",z_3,", ",z_4)
```

How coud I select the `z_i`

according to the inequality sign and construct 2 sets.