A car drives from A to B with a speed of 50km/h when going there and a speed of 60km/h when returning. It takes 11 hours to go back and forth. What is the distance in km between A and B?
汽车从甲地开往乙地，去时的速度是50km/h，返回时的速度是60km/h，来回一共用了11h．甲乙两地的距离是多少km．
<gadget id="calculator">1 / 50</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/50) + (1/60)</gadget>
<output>11/300 = around 0.036667</output>

<gadget id="calculator">11 / (11/300)</gadget>
<output>300</output>

<result>300</result>