On an order of 3 dozen boxes of a consumer product, a retailer receives an extra dozen free. This is equivalent to allowing him a discount of:  Pick:  A) 20 %  B) 25 %  C) 30 %  D) 35 %  E) 40 %

Rationale: clearly , the retailer gets 1 dozen out of 4 dozens free . equivalent discount = 1 / 4 * 100 = 25 % . answer b ) 25 %
Answer: B