If the still water speed of a ship is 32 kilometers per hour, and it takes 4 hours to sail 144 kilometers along the river, what is the current speed of the river in kilometers per hour?
一艘轮船的静水速度为每小时32千米，在河中顺水航行144千米用了4小时，那么这条河的水流速度是每小时多少千米．
<gadget id="calculator">144 / 4</gadget>
<output>36</output>

<gadget id="calculator">36 - 32</gadget>
<output>4</output>

<result>4</result>