A certain brand of milk is 12 yuan per bag. During the promotion period, buy 6 bags and get 2 bags free. Mom bought 6 bags. How much is each bag cheaper?
某品牌牛奶每袋12元，促销期间买6袋赠2袋，妈妈买了6袋，每袋便宜了多少钱？
<gadget id="calculator">6 / 8</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">12 * (3/4)</gadget>
<output>9</output>

<gadget id="calculator">12 - 9</gadget>
<output>3</output>

<result>3</result>