A shopkeeper allows 20% off on the marked price of goods and still gets a profit of 25%. What is the actual cost to him of an article marked Rs. 500?
Marked price (M.P) of an article = Rs. 500
Discount allowed =20%
∴ Selling price (S.P) =M.P×(100−Discount%)100
=Rs.500×(100−20)100=Rs.500×80100=Rs.400
Gain =25%
∴ C.P =S.P×100100+gain%
=400×100100+25=Rs.400×100125=Rs.320