The fuel carried by an aircraft can support the aircraft to fly for up to 6 hours. When the aircraft goes with the wind, it can fly 1500 kilometers per hour; when it flies back against the wind, it can fly 1200 kilometers per hour. How many kilometers can this aircraft fly at most? Just need to fly back? (Solve with ratio)
一架飞机所带的燃料最多可以支持飞机飞行6小时，飞机去时顺风，每小时可以飞行1500千米；飞回时逆风，每小时可以飞行1200千米，这架飞机最多飞行多少千米，就需要往回飞？(用比例解)
<gadget id="calculator">1_500 * 6</gadget>
<output>9_000</output>

<gadget id="calculator">1_200 + 1_500</gadget>
<output>2_700</output>

<gadget id="calculator">9_000 / 2_700</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">1_200 * (10/3)</gadget>
<output>4_000</output>

<result>4_000</result>