A tourist draws a small boat from the pier at 14:15, and he plans to return to the pier no later than 17:00. The current velocity of the river is 1.2 kilometers per hour, and the speed of the boat in still water is 3 kilometers per hour. Row for 30 minutes and rest for 15 minutes, do not change direction halfway, and row back after a certain rest. Q: How many kilometers can he row away from the pier at most?
某游客在14时15分由码头划出一条小船，他计划不迟于17时回到码头，河水的流速为每小时1.2千米，小船在静水中的速度为每小时3千米，他每划30分钟就休息15分钟，中途不改变方向，并在某次休息后往回划．问：他最多能划离码头多少千米？
<gadget id="calculator">3 + 1.2</gadget>
<output>4.2</output>

<gadget id="calculator">4.2 * 0.5</gadget>
<output>2.1</output>

<result>2.1</result>