The speed of a ship in still water is 15 kilometers per hour. It sails against the current for 11 hours and travels 88 kilometers. How many hours does it take for the ship to return?
一艘轮船在静水中的速度是每小时15公里，它逆水航行11小时走了88公里，这艘船返回需多少小时．
<gadget id="calculator">88 / 11</gadget>
<output>8</output>

<gadget id="calculator">15 - 8</gadget>
<output>7</output>

<gadget id="calculator">15 + 7</gadget>
<output>22</output>

<gadget id="calculator">88 / 22</gadget>
<output>4</output>

<result>4</result>