A certain brand of toothpaste is 8 yuan per box, and the supermarket implements a promotional activity to buy 3 and get 1 free. Teacher Li bought 3 boxes at one time, how much is each box cheaper?
某种品牌的牙膏每盒8元，超市实行促销活动买3送1．李老师一次性买了3盒，每盒便宜多少元？
<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">8 * (3/4)</gadget>
<output>6</output>

<gadget id="calculator">8 - 6</gadget>
<output>2</output>

<result>2</result>