Xiaoqiang's family ordered 2 bags of milk every day in April, and paid a total of 60 yuan at the wholesale price. The retail price of this milk is 1.20 yuan per bag, so how much cheaper is the wholesale price per bag than the retail price?
小强家四月份每天预订2袋牛奶，按批发价共付60元．这种牛奶每袋零售价是1.20元，这样每袋批发价比零售价便宜多少元？
<gadget id="calculator">2 * 30</gadget>
<output>60</output>

<gadget id="calculator">60 / 60</gadget>
<output>1</output>

<gadget id="calculator">1.2 - 1</gadget>
<output>0.2</output>

<result>0.2</result>