A shopkeeper expects a gain of 25% on his cost price. If in a week, his sale was Tk. 1600, what was his profit?

Question: A shopkeeper expects a gain of 25% on his cost price. If in a week, his sale was Tk. 1600, what was his profit?Solution:Let the cost price be x∴ The selling price = {x + (25% of x)}ATQ,x + (25% of x) = 1600⇒ x + (25x/100) = 1600⇒ x + (x/4) = 1600⇒ (4x + x)/4 = 1600⇒ 5x = 1600 × 4⇒ x = (1600 × 4)/5∴ x = 1280∴ Profit = (1600 - 1280) = Tk. 320