A building contractor can source door frames from either a nearby shop or a far-off forest area. The cost details are as summarized in the following table. The total requirement of wood for the construction work is 75 tons.

Items Nearby shop Far-off forest area

Distance to site Negligible 900 km Transportation cost per ton per km Negligible Rs. 100 Material cost/ton Rs. 2,000 Rs. 1,250

Find the best alternative for buying the wooden frames. Also find the economic advantage of the best decision.