The diesel oil carried by a ship can be used for up to 6 hours. When sailing out with the wind, it can travel 30 kilometers per hour; when it sails back against the wind, it can travel 24 kilometers per hour. How many kilometers should the ship sail at most before turning back?
一艘轮船所带的柴油最多可以用6小时，驶出时顺风，每小时行30千米；驶回时逆风，每小时行24千米．这艘轮船最多驶出多少千米就应返航？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 24</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/30) + (1/24)</gadget>
<output>3/40 = around 0.075</output>

<gadget id="calculator">6 / (3/40)</gadget>
<output>80</output>

<result>80</result>