If the cost price of 10 articles is equal to the selling price of 20 articles, what is the % profit or loss made by the merchant?  Choose the correct choice from the following choices.
A) 25% loss
B) 25% profit
C) 20% loss
D) 20% profit
E) 50% loss
Let the cost price of 1 article be $1.   Therefore, cost price of 10 articles = 10 * 1= 
<gadget id="calculator">10 * 1</gadget>
<output>10</output>
$10   The selling price of 20 articles= cost price of 10 articles = $10.   Now, we know the selling price of 20 articles. Let us find the cost price of 20 articles.   Cost price of 20 articles = 20 * 1= 
<gadget id="calculator">20 * 1</gadget>
<output>20</output>
$20.   Therefore, profit made on sale of 20 articles= Selling price of 20 articles - cost price of 20 articles   = 10 - 20 = -$10.   As the profit is in the negative, the merchant has made a loss of $10.   Therefore, % loss = loss/cp * 100   % loss = -10/20 * 100 = 50% loss.   50% loss
<result>E</result>
If the cost price of 10 articles is equal to the selling price of 20 articles, what is the % profit or loss made by the merchant?