John paid a sum of money for purchasing 30 pens, which he recovered in full when he sold 20 of them. What was his percentage of profit or loss per pen?	Options:
A) 50% B) 60% C) 40% D) 30% E) 45%
A   50%   If the sum he paid whilst purchasing 30 pens = A,   Then the Cost Price of each pen = A/30.   Since the amount he got whilst selling 20 pens is also = A   Then the Selling Price of each pen = A/20.   Since Selling Price &gt; Cost Price, he made a profit.   Profit per pen = Selling Price - Cost Price = A/20 - A/30 = A/60.   Profit percentage per pen = Profit per pen / Cost per pen x 100 = (50%/60) / (50%/30) x 100 = 50%
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John paid a sum of money for purchasing 30 pens, which he recovered in full when he sold 20 of them. What was his percentage of profit or loss per pen?