It takes 12 hours for a ship to sail from Pier A to Pier B and back again. When going forward, the speed is 200 km/h, and when coming back, the speed is 100 km/h. Ask how many kilometers are there between the two piers of A and B?
一艘轮船从甲码头开往乙码头，再返回一共用了12小时．去时顺流，速度为200千米/时，回来时逆流，速度为100千米/时．问甲乙两码头相距多少千米？
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12 * (1/3)</gadget>
<output>4</output>

<gadget id="calculator">200 * 4</gadget>
<output>800</output>

<result>800</result>