One kind of milk is 1.5 yuan per bag. Xiaohua’s family ordered 1 bag of milk every day in May, and paid a total of 40.3 yuan according to the wholesale price. How much cheaper is this per bag than the retail price?
一种牛奶每袋1.5元，小华家五月份每天预订1袋牛奶，按批发价，共付40.3元．这样每袋比零售价便宜多少元？
<gadget id="calculator">40.3 / 31</gadget>
<output>1.3</output>

<gadget id="calculator">1.5 - 1.3</gadget>
<output>0.2</output>

<result>0.2</result>