An enemy plane violated our airspace, and our air force immediately took off to meet it. When the distance between the two planes was 49 kilometers, the enemy plane turned its nose and fled at a speed of 15 km/min. Our army followed it at a speed of 22 km/min. In the pursuit of the escape route, when our army chased the enemy 1 kilometer away, we started a fierce battle with the enemy plane and defeated the enemy plane in only 0.5 minutes. How many minutes did it take for the enemy plane to escape and be annihilated by our army?
一架敌机侵犯我领空，我空军立即起飞迎击，在两机相距49千米时，敌机扭转机头以15千米/分的速度逃跑，我军以22千米/分的速度沿其逃跑路线追击，当我军追至敌军1千米时，与敌机展开激战，只用0.5分钟就击垮了敌机，敌机从逃跑到被我军歼灭共用几分钟？
<gadget id="calculator">57 / 7</gadget>
<output>57/7 = around 8.142857</output>

<result>57/7 = around 8.142857</result>