It is 750 kilometers from Chongqing to Guizhou, and a truck has traveled 210 kilometers at an average of 45 kilometers per hour. How many hours will it take to reach Guizhou?
从重庆到贵州有750千米，一辆卡车已经行了210千米，平均每小时行45千米．还要几小时才能到达贵州？
<gadget id="calculator">750 - 210</gadget>
<output>540</output>

<gadget id="calculator">540 / 45</gadget>
<output>12</output>

<result>12</result>