Chapter 6, Problem 16RE

In Exercises 9-18, solve the given linear programming problem using the simplex method. If no optimal solution exists, indicate whether the feasible region is empty or the objective function is unbounded.

Minimize $c=x+y-z$

Subject to $3x+2y+z\ge 60$

$2x+y+3z\ge 60$

$x+3y+2z\ge 60$

$x\ge 0,y\ge 0,z\ge 0$.