Consider the problem
Maximize z = 2x1 + 4x2 + 4x3 - 3x4
Subject to
X1 + x2 + x3 = 4
X1 + 4x2 + x4 = 8
X1, x2, x3, x4 ≥ 0
The problem shows that x3 and x4 can play the role of slacks for the two equations. They differ from slacks in that they have nonzero