Chapter 6.3, Problem 2ED

The simplex method can be used to solve any standard maximization problem. Which of the following minimization problems have dual problems that are standard maximization problems? (Do not solve the problems.)

$\begin{array}{l}\left(\text{A}\right)\text{Minimize }C=2x_1+3x_2\\ \text{ subject to }2x_1-5x_2\ge 4\\ x_1-3x_2\ge -6\\ x_1,x_2\ge 0\\ \\ \left(\text{B}\right)\text{Minimize }C=2x_1-3x_2\\ \text{ subject to }-2x_1+5x_2\ge 4\\ -x_1+3x_2\ge 6\\ x_1,x_2\ge 0\end{array}$

What conditions must a minimization problem satisfy so that its dual problem is a standard maximization problem?