Let the number of large vans and small vans used for transporting the packages be x and y, respectively.
It is given that the cost of engaging each large van is ₹400 and each small van is ₹200.
Cost of engaging x large vans = ₹400x
Cost of engaging y small vans = ₹200y
Let Z be the total cost of engaging x large vans and y small vans.
∴ Z = ₹(400x + 200y)
The firm has to transport at least 1200 packages daily using large vans which carry 200 packages each and small vans which can take 80 packages each.
∴ Number of packages transported by x large vehicles + Number of packages transported by y small vehicles ≥ 1200
⇒ 200x + 80y ≥ 1200
Not more than ₹3000 is to be spent daily on the transportation.
∴ 400x + 200y ≤ 3000
Also, the number of large vans cannot exceed the number of small vans.
∴ x ≤ y
Thus, the linear programming problem of the given problem is
Minimise Z = ₹(400x + 200y)
Subject to constraints
200x + 80y ≥ 1200
400x + 200y ≤ 3000
x ≤ y
x ≥ 0, y ≥ 0