Limin shopping mall has promotional activities on weekends, washing powder is 16 yuan per bag, buy 3 bags and get 1 bag free. How much is this kind of promotion actually per bag?
利民商场周末搞促销活动，洗衣粉每袋16元，买3袋送1袋．这样的促销活动实际每袋是多少元？
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">16 * (3/4)</gadget>
<output>12</output>

<result>12</result>