The speed of the boat in still water is 14km/h, and the speed of the current is 2km/h. The boat sails downstream from a pier first, and then returns upstream. If the boat returns within 3h30min, how far can the boat travel?
船在静水中的速度是14km/h，水流速度是2km/h，船先顺流由一码头开出，再逆流返回，若要船在3h30min内返回，那么船最远能开出多远？
<gadget id="calculator">3.5 * 14 * 14</gadget>
<output>686</output>

<gadget id="calculator">3.5 * 2 * 14</gadget>
<output>98</output>

<gadget id="calculator">3.5 * 14 * 2</gadget>
<output>98</output>

<gadget id="calculator">3.5 * 2 * 2</gadget>
<output>14</output>

<gadget id="calculator">98 - 98 - 14</gadget>
<output>-14</output>

<gadget id="calculator">686 + (-14)</gadget>
<output>672</output>

<gadget id="calculator">2 - 2</gadget>
<output>0</output>

<gadget id="calculator">14 + 14 + 0</gadget>
<output>28</output>

<gadget id="calculator">672 / 28</gadget>
<output>24</output>

<result>24</result>