A firm has to transport $1200$ packages using large vans which can carry $200$ packages each and small vans which can take $80$ packages each.The cost for engaging each large van is Rs $ 400$ and each small van is Rs $200$.Not more than Rs $3000$ is to be spent on the job and the number of large vans cannot exceed the number of small vans.Formulate this problem as a LPP given that the objective is to minimize cost.
Here the solution is also given. But I am not understanding why is the restriction for cost (2nd restriction) $400x+200y≥3000$ ? It seems to me $400x+200y\le3000$ is appropriate. Am I doing wrong?