The distance between A and B is 315 kilometers. A car has been driving from A to B for 3 hours, and the remaining distance is 45 kilometers longer than the previous one. How many hours will it take to complete the journey?
甲、乙两地相距315千米，一辆汽车从甲地开往乙地，已经行驶了3小时，剩下的路程比已经行的多45千米，行完全程一共需几小时？
<gadget id="calculator">315 - 45</gadget>
<output>270</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">270 / 6</gadget>
<output>45</output>

<gadget id="calculator">315 / 45</gadget>
<output>7</output>

<result>7</result>