The old woman sells eggs, interesting and generous. She sells half of them and gives half a box of eggs. I met 4 people and sold out all the eggs in the box. How many boxes of eggs are in the box?
老妇卖鸡蛋，有趣又大方，见人卖一半，还送半盒蛋，见了4个人，卖光箱中蛋，请问箱中蛋几盒？
<gadget id="calculator">0.5 * 2</gadget>
<output>1</output>

<gadget id="calculator">1 + 0.5</gadget>
<output>1.5</output>

<gadget id="calculator">1.5 * 2</gadget>
<output>3</output>

<gadget id="calculator">3 + 0.5</gadget>
<output>3.5</output>

<gadget id="calculator">3.5 * 2</gadget>
<output>7</output>

<gadget id="calculator">7 + 0.5</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 * 2</gadget>
<output>15</output>

<result>15</result>