A car drove from Guanghua Village to the county seat, traveling 42 kilometers per hour. Since the driver did not know the route, it was only 2 hours after driving that he realized that he had driven 15 kilometers away from the county seat. How many kilometers is the road from Guanghua Village to the county seat?
一辆汽车从光华村开往县城，每小时行42千米，由于司机对路线不悉，开出2小时后才发现已经开出县城15千米．光华村到县城的公路长多少千米？
<gadget id="calculator">42 * 2</gadget>
<output>84</output>

<gadget id="calculator">84 - 15</gadget>
<output>69</output>

<result>69</result>