On an order of 4 dozen boxes of a consumer product, a retailer receives an extra dozen free. This is equivalent to allowing him a discount of:  Choose the correct choice from the following choices:
A) 10%
B) 20%
C) 30%
D) 40%
E) 50%
Clearly, the retailer gets 1 dozen out of 5 dozens free.   Equivalent discount = 1/5 * 100= 
<gadget id="calculator">1/5 * 100</gadget>
<output>20</output>
20%.   Answer 20%) 20%
<result>B</result>
On an order of 4 dozen boxes of a consumer product, a retailer receives an extra dozen free. This is equivalent to allowing him a discount of: