Chapter 6.4, Problem 32E

Problems 25-32 are mixed. Some can be solved by the methods presented in Sections 6.2 and 6.3 while others must be solved by the big $M$ method.

$\begin{array}{l}\text{Minimize }C=10x_1+12x_2+28x_3\\ \text{subject to }4x_1+2x_2+3x_3\ge 20\\ \text{ 2}{x}_1-x_2-4x_3\le 10\\ x_1,x_2,x_3\ge 0\end{array}$