A car travels between A and B. The average travel time is 50 kilometers per hour when going there, and 60 kilometers per hour when returning. How many kilometers per hour does the car travel between the two places on average?
汽车往返甲、乙两地．去的时候平均每小时行50千米，返回的时候平均每小时行60千米，汽车往返两地平均每小时行多少千米？
<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<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">2 / (11/300)</gadget>
<output>600/11 = around 54.545455</output>

<result>600/11 = around 54.545455</result>