Problem: if the cost price of 20 articles is equal to the selling price of 25 articles , what is the % profit or % loss made by the merchant ?
Rationale: "explanatory answer approach : assume a value for cost price . compute cost price and selling price for the same number of articles let the cost price of 1 article be $ 1 . therefore , cost price of 20 articles = 20 * 1 = $ 20 the selling price of 25 articles = cost price of 20 articles = $ 20 . let us find the cost price of 25 articles . cost price of 25 articles = 25 * 1 = $ 25 . therefore , profit made on sale of 25 articles = selling price of 25 articles - cost price of 25 articles = 20 - 25 = - $ 5 . because the profit is in the negative , the merchant has made a loss of $ 5 . therefore , % loss = loss / cost price ∗ 100 % loss = 5 / 25 ∗ 100 = 20 % loss . choice c"
annotated_formula: multiply(const_100, divide(subtract(const_100, divide(multiply(const_100, 25), 20)), divide(multiply(const_100, 25), 20)))