A truck transports goods from the county town to the mountain. It takes a total of 20 hours to go back and forth. The time it takes to go is 1.5 times that of the time it comes back. It is known that the time it takes to go is 12 kilometers slower than the time when it comes back. Find the round-trip distance.
一辆货车从县城往山里运货，往返共走20小时，去时所用时间是回来时的1.5倍，已知去时每小时比回来时慢12千米，求往返的路程．
<gadget id="calculator">1 + 1.5</gadget>
<output>2.5</output>

<gadget id="calculator">20 / 2.5</gadget>
<output>8</output>

<gadget id="calculator">20 - 8</gadget>
<output>12</output>

<gadget id="calculator">12 * 12</gadget>
<output>144</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<gadget id="calculator">144 / 4</gadget>
<output>36</output>

<gadget id="calculator">36 * 8 * 2</gadget>
<output>576</output>

<result>576</result>