Step 1: Given one non-trivial constraint is \( x + 2y \geq 100 \). From the graph:
- The line passing through \( A(0, 50) \) and \( E(100, 0) \) corresponds to \( x + 2y = 100 \).
- The line passing through \( B(20, 40) \) and \( C(50, 100) \) corresponds to \( y - \frac{4}{3}x + \frac{80}{3} \geq 0 \).
- The line passing through \( C(50, 100) \) and \( D(0, 200) \) corresponds to \( y - 2x \leq 0 \).
Final Answer: The other two non-trivial constraints are: \[ y - \frac{4}{3}x + \frac{80}{3} \geq 0 \quad {and} \quad y - 2x \leq 0. \]
The system of simultaneous linear equations :
\[ \begin{array}{rcl} x - 2y + 3z &=& 4 \\ 2x + 3y + z &=& 6 \\ 3x + y - 2z &=& 7 \end{array} \]