Liya Supermarket held a promotion on weekends. A kind of washing powder was 12 yuan per bag, buy 4 bags and get 1 bag free. Mom bought 4 bags of this washing powder at a time. How much is each bag cheaper than usual?
丽雅超市周末搞促销活动，一种洗衣粉每袋12元，买4袋送1袋．妈妈一次买了4袋这种洗衣粉，每袋比平时便宜多少元？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">12 * (4/5)</gadget>
<output>48/5 = around 9.6</output>

<gadget id="calculator">12 - (48/5)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>