Find the dual of the following primal problem [5M]
Minimize z= 60x₁ + 10x2 + 20x3
Subject to 3x1 + x₂ + x3 ≥ 2
x₁ - x₂ + x3 ≥-1
X₁ + 2x₂ - X3 ≥ 1,
X1, X2, X3 ≥ 0."