Final answer:
To find the gain percentage when a clock is sold for Rs.204, we use the formula to calculate cost price given the selling price and gain percentage. As the selling price is constant, the gain percentage remains at 25%.
Step-by-step explanation:
The question asks about the percentage gain a dealer would have by selling a clock for Rs.204 if his original gain at the same price was 25%. To calculate the cost price, we can use the formula Cost Price = Selling Price / (1 + Gain Percent/100). If the dealer sells the clock for Rs.204 and gains 25%, the cost price would be Rs.204 / (1 + 25/100), which calculates to Rs.163.20 (rounded to two decimal places). As the dealer already sells the clock for Rs.204, the gain won't change with the same selling price, so the gain percentage remains 25%. However, if we are to determine what the percentage gain would be if the cost price or selling price changed, similar calculations applying respective formulas would be needed based on the proposed scenarios.