A． The distance between the two scenic spots B is 10 kilometers. A sightseeing cruise ship departs from scenic spot A and returns immediately after arriving at scenic spot B. It takes 3 hours. It is known that the first hour travels 8 kilometers longer than the third hour, so how many kilometers per hour is the water speed.
A．B两景点相距10千米，一艘观光游船从A景点出发抵达B景点后立即返回，共用3小时．已知第一小时比第三小时多行8千米，那么水速为每小时多少千米．
<gadget id="calculator">10 - 8</gadget>
<output>2</output>

<gadget id="calculator">10 + 2</gadget>
<output>12</output>

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

<gadget id="calculator">10 / 4</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">3 - (5/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">10 / (1/2)</gadget>
<output>20</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<result>8</result>