An enemy plane violated our airspace, and our plane immediately took off to meet it. When the distance between the two planes was 50 kilometers, the enemy plane turned its nose and fled at a speed of 15 kilometers per minute. Our plane pursued it at a speed of 22 kilometers per minute. When our plane chased the enemy plane 1 km away, it fought fiercely with the enemy plane, and shot down the enemy plane in only half a minute. How many points did it take for the enemy plane to turn around and flee to being shot down?
一架敌机侵犯我领空，我机立即起飞迎击，在两机相距50千米时，敌机扭转机头以每分15千米的速度逃跑，我机以每分22千米的速度追击，当我机追至敌机1千米时与敌机激战，只用了半分就将敌机击落．敌机从扭头逃跑到被击落共用了多少分？
<gadget id="calculator">50 - 1</gadget>
<output>49</output>

<gadget id="calculator">22 - 15</gadget>
<output>7</output>

<gadget id="calculator">49 / 7</gadget>
<output>7</output>

<gadget id="calculator">7 + 0.5</gadget>
<output>7.5</output>

<result>7.5</result>