Solve the following linear programming model graphically and explain the solution result:
minimize Z = +3,000x1 + 1,000x2
subject to
60x1 + 20x2 ≥ 1,200
10x1 + 10x2 ≥ 400
40x1 + 160x2 ≥ 2,400
x1, x2 ≥ 0