The distance between A and B is 245 kilometers. A person rides a bicycle from A to B. It takes 4 hours to go there, and it takes 3 hours to speed up when returning. How many kilometers per hour does he travel on average for a round trip?
甲、乙两地相距245千米，某人骑自行车，从甲地到乙地，去时用了4小时，回来时加快速度用了3小时．他往返一次平均每小时行多少千米？
<gadget id="calculator">245 * 2</gadget>
<output>490</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">490 / 7</gadget>
<output>70</output>

<result>70</result>