A and B start from A and B and walk towards each other. A starts 2 hours first, and they meet 4 hours after B starts. It is known that A travels 4 kilometers more per hour than B, and the meeting point is 20 kilometers away from the midpoint of AB, how many kilometers is the distance between AB and AB?
甲、乙两人从A、B两地出发相向而行，甲先出发2小时，两人在乙出发4小时后相遇．已知甲比乙每小时多行4千米，而相遇地点距离AB的中点20千米，则AB两地相距多少千米？
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">40 - 8 - 16</gadget>
<output>16</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

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

<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">72 + 32</gadget>
<output>104</output>

<result>104</result>