100 PTS! SHOW ALL STEPS IN YOUR WORK AND REASONING PLEASE!
1. Solve the system by substitution.
[tex]\left \{ {{-x-y-z=-8} \atop {-4x+4y+5z=7; 2x+2z=4}} \right.[/tex]

2. Solve the system by elimination.
[tex]\left \{ {{-2x+2y+3z=0} \atop {-2x-y+z=-3; 2x+3y+3z=5}} \right.[/tex]

3. Given the system of constraints, name all vertices of the feasible region. Then find the maximum value of the given objective function.
Constraints [tex]\left \{ {{x\geq 0;y\geq 0} \atop {y\leq \frac{1}{3}x+3;5\geq x+y }} \right.[/tex]
Objective Function: [tex]C=6x-4y[/tex]