The milk company is running a promotion. Originally, each bottle of milk was priced at 8 yuan. Now buy three bottles and get one free. If you buy 3 bottles at a time, how much is each bottle cheaper than the original?
牛奶公司搞促销，原来每瓶牛奶售价8元，现在买三瓶送一瓶．如果一次买3瓶，那么每瓶比原来便宜多少钱？
<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>