The quantity of rice in warehouse A and warehouse B is the same. It will take 10 days, 12 days and 15 days for father, mother and Yang Yang to transport one warehouse of rice respectively. Mom and Dad started to transport the rice from warehouses A and B respectively at the same time. Yang Yang helped mother first and then father. As a result, the rice from both warehouses was transported at the same time. How many days did Yang Yang help mother transport?
甲、乙两仓的稻谷数量一样，爸爸，妈妈和阳阳单独运完一仓稻谷分别需要10天，12天和15天．爸爸妈妈同时开始分别运甲、乙两仓的稻谷，阳阳先帮妈妈，后帮爸爸，结果同时运完两仓稻谷，那么阳阳帮妈妈运了多少天．
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/12) + (1/15)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / (1/4)</gadget>
<output>8</output>

<gadget id="calculator">(1/12) * 8</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / (1/15)</gadget>
<output>5</output>

<result>5</result>