The distance between the two piers is 108km. It takes 10 hours for a ship to travel along the current and 12 hours to travel against the current. What is the speed of the ship in still water?
两码头相距108km，一艘轮船顺水行完全程需10小时，逆水行完全程需12小时，这艘轮船的静水速度是多少．
<gadget id="calculator">108 / 10</gadget>
<output>54/5 = around 10.8</output>

<gadget id="calculator">108 / 12</gadget>
<output>9</output>

<gadget id="calculator">(54/5) + 9</gadget>
<output>99/5 = around 19.8</output>

<gadget id="calculator">(99/5) / 2</gadget>
<output>99/10 = around 9.9</output>

<result>99/10 = around 9.9</result>