missile advances at the speed of sound (330 meters per second). It is known that two planes are flying in the same direction at a distance of 1500 meters. The speed of the plane in front is 210 meters per second, and the speed of the plane behind is 180 meters per second. When the following aircraft launches a missile, how many seconds can it hit the previous aircraft?
一种导弹以音速(每秒330米)前进，已知两架飞机相距1500米同向飞行，前面一架飞机的速度是每秒210米，后面一架飞机的速度是每秒180米．当后面的飞机发出导弹时，多少秒可以击中前一架飞机．
<gadget id="calculator">330 + 180</gadget>
<output>510</output>

<gadget id="calculator">510 - 210</gadget>
<output>300</output>

<gadget id="calculator">1_500 / 300</gadget>
<output>5</output>

<result>5</result>