A boat sails downstream at a speed of 30 km/h, and it is known that sailing downstream for 3 hours is equal to sailing upstream for 5 hours, so how many kilometers does the boat travel downstream for 1 hour?
一只船顺流而行的航速为30千米/小时，已知顺水航行3小时和逆水航行5小时的航程相等，则此船顺水漂流1小时的航程为多少千米．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 * (3/5)</gadget>
<output>18</output>

<gadget id="calculator">30 - 18</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>