In order to exercise, Panda Panda walks for 3 hours every day. He first walks on the flat road, then goes up the mountain, and finally returns along the same road. Panda Panda walks 4 kilometers per hour on flat roads, 3 kilometers per hour uphill, and 6 kilometers per hour downhill. During daily exercise, how many kilometers does he walk in total?
熊猫胖胖为了锻炼身体，每天步行3小时，他先走平路，然后上山，最后又沿原路返回．熊猫胖胖在平路上每小时行4千米，上山每小时行3千米，下山每小时行6千米，在每天锻炼中，他共行走多少千米？
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<result>6</result>