Answer:
10
Explanation:
You want the minimum value of c = x +y, subject to the constraints {2x +y ≥ 20, 2x +3y ≥ 0, x ≥ 0, y ≥ 0}.
Graph
The attached graph shows the relevant vertices of the feasible region are (0, 20) and (10, 0). The value of c is minimized when (x, y) = (10, 0). At that point, c = 10 + 0 = 10.
The minimum value of c is 10.