Xiaoming's family ordered 2 bags of fresh-keeping milk every day in June, and paid a total of 57 yuan at the wholesale price. The retail price of this kind of fresh milk is 1.10 yuan per bag, so how much cheaper is the wholesale price per bag than the retail price?
小明家六月份每天预定2袋保鲜奶，按批发价共付57元．这种保鲜奶每袋零售价是1.10元，这样每袋批发价比零售价便宜多少元？
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">57 / 60</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">1.1 - (19/20)</gadget>
<output>0.15</output>

<result>0.15</result>