The distance between port A and port B is 126 meters. It takes 7 hours for a ship to travel from port A to port B along the current. The water speed is known to be 2 kilometers per hour. How long does it take for the ship to return from port B to port A against the current?
甲港到乙港相距126米，有一只船顺水从甲港到乙港需要7小时，已知水速每小时2千米，该船逆水从乙港返回甲港要几小时？
<gadget id="calculator">126 / 7</gadget>
<output>18</output>

<gadget id="calculator">18 - 2 - 2</gadget>
<output>14</output>

<gadget id="calculator">126 / 14</gadget>
<output>9</output>

<result>9</result>