There is a special price for washing powder in the supermarket. The original price is 8 yuan a bag. Now buy 3 bags and get 1 bag free. How much is each bag cheaper?
超市洗衣粉特价，原价8元一袋，现在买3袋送1袋，每袋便宜多少钱？
<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>