Our People's Liberation Army pursued a fleeing enemy. The enemy began to flee from A at a speed of 10 kilometers per hour at 16:00. The PLA received an order at 22:00 to start from B at a speed of 30 kilometers per hour. chase. It is known that A and B are 60 kilometers apart, how many hours can the PLA catch up with the enemy?
我人民解放军追击一股逃窜的敌人，敌人在下午16点开始从甲地以每小时10千米的速度逃跑，解放军在晚上22点接到命令，以每小时30千米的速度开始从乙地追击．已知甲乙两地相距60千米，问解放军几个小时可以追上敌人？
<gadget id="calculator">22 - 16</gadget>
<output>6</output>

<gadget id="calculator">6 * 10</gadget>
<output>60</output>

<gadget id="calculator">60 + 60</gadget>
<output>120</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">120 / 20</gadget>
<output>6</output>

<result>6</result>