ship sails down the river from A to B at a speed of 65 km/h and arrives in 8 hours. It took 10 hours to go upstream when returning, what is the average speed of the ship when returning?
一艘轮船沿江顺流而下以65千米/时的速度从甲地开往乙地，8小时到达．返回时逆流而上，用了10小时，这艘轮船返回时的平均速度是多少千米/时？
<gadget id="calculator">8 / 10</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">65 * (4/5)</gadget>
<output>52</output>

<result>52</result>