It takes 2 hours for a boat to go from A to B along the waterway. Going smoothly, sailing 8 kilometers more per hour than returning, and sailing 6 kilometers less in the second hour than in the first hour. Find the distance between A and B by water.
一条船从甲地沿水路去乙地，往返一次共需2小时．去时顺水，比返回时每小时多航行8千米，且第二小时比第一小时少航行6千米．求甲、乙两地水路的距离．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">12 + 3</gadget>
<output>15</output>

<result>15</result>