A certain boat is traveling at a speed of 10 kilometers per hour, and the speed of the water is how many kilometers per hour. It travels upstream for 40 kilometers in 5 hours.
某船的航行速度是每小时10千米，水流速度是每小时多少千米，逆水上行5小时行40千米．
<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">10 - 8</gadget>
<output>2</output>

<result>2</result>