Two people, A and B, race around the lake in the same direction. The length of a circle around the lake is 900 meters. A walks 60 meters per minute. B’s speed per minute is 30 meters less than twice that of A. B is 180 meters ahead of A. Ask: How many minutes elapsed before the two met for the first time?
甲、乙两人环湖同向竞走，环湖一周的长度是900米，甲每分钟走60米，乙每分钟的速度比甲的2倍少30米，乙在甲前面180米，问：经过多少分钟后两人第一次相遇？
<gadget id="calculator">900 - 180</gadget>
<output>720</output>

<gadget id="calculator">60 * 2</gadget>
<output>120</output>

<gadget id="calculator">120 - 30</gadget>
<output>90</output>

<gadget id="calculator">90 - 60</gadget>
<output>30</output>

<gadget id="calculator">720 / 30</gadget>
<output>24</output>

<result>24</result>