A person travels from place A to place B. He originally planned to drive 60 kilometers per hour, and he can return to place A on time. However, when he drives to place B, he finds that the speed is 55 kilometers per hour. If he wants to return on time, How many kilometers per hour should he travel?
某人从甲地到乙地，原计划每小时行60千米，可按时返回甲地，但车开到乙地后时，发现来时的速度是每小时55千米，若要按时返回，他应每小时行多少千米？
<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/60) * 2</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 55</gadget>
<output>1/55 = around 0.018182</output>

<gadget id="calculator">(1/30) - (1/55)</gadget>
<output>1/66 = around 0.015152</output>

<gadget id="calculator">1 / (1/66)</gadget>
<output>66</output>

<result>66</result>