There is a man who likes to drink very much. He buys wine every time he passes by a hotel. This man went out with a wine gourd, and when he saw a hotel, he doubled the wine in the wine gourd, and then drank 8 taels of wine. He met a total of 3 hotels that day, and after drinking in the last hotel, the gourd The wine was just finished. Question: How many wines are there in the wine gourd?
有一个人非常喜欢喝酒，他每经过一个酒店都要买酒喝．这个人出门带了一个酒葫芦，看到一个酒店就把酒葫芦中的酒加一倍，然后喝下8两酒，这天他一共遇到3家酒店，在最后一家酒店喝完酒后，葫芦里的酒刚好喝完．问：原来酒葫芦里有多少两酒？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 8</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 + 8</gadget>
<output>14</output>

<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<result>7</result>