A hardware trader makes a profit of 25% on every item he sells. The cost price of 20 such items equals the selling price of how many items?

With a cost of ₹100 an item sells for ₹125, so 20 items cost ₹2000 and that money buys 2000/125 = 16 items at the selling price. (The right move is to DIVIDE 20 by 1.25. Subtracting 25% of 20 gives 15, multiplying 20 by 1.2 gives 24, and answering 25 simply repeats the profit rate as though it were a count.)