A store shipped in 80 exercise books for a total purchase price of 40 yuan. If you want to make a profit of 0.2 yuan per exercise book, how much should the retail price of each exercise book be?
某商店运进80本练习本，进货价共计40元．要想每本练习本盈利0.2元，每本练习本的零售价应定为多少元．
<gadget id="calculator">40 / 80</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) + 0.2</gadget>
<output>0.7</output>

<result>0.7</result>