The length of the railway between two cities is 516 kilometers. Two cars, A and B, depart from the two cities at the same time and meet each other after 4 hours. Car A travels 61 kilometers per hour. How many kilometers does car B travel per hour?
两个城市间铁路长516千米，甲、乙两车同时从两个城市出发，4小时后相遇，甲车每小时行61千米，乙车每小时行多少千米？
<gadget id="calculator">516 / 4</gadget>
<output>129</output>

<gadget id="calculator">129 - 61</gadget>
<output>68</output>

<result>68</result>