The distance between A and B is 3600 meters. A and B start from A, and C start from B, facing each other at the same time. A walks 80 meters per minute, C walks 100 meters per minute, and C meets B 4 minutes after meeting A. How many meters does B walk per minute? (answer in two ways)
A、B两地相距3600米．甲乙从A地，丙从B地，同时相向出发．甲每分钟走80米，丙每分钟走100米，丙遇到甲4分钟后再遇到乙．乙每分钟走多少米？(用两种方法解答)
<gadget id="calculator">3_600 * 100</gadget>
<output>360_000</output>

<gadget id="calculator">3_600 * 80</gadget>
<output>288_000</output>

<gadget id="calculator">4 * 100 * 100</gadget>
<output>40_000</output>

<gadget id="calculator">4 * 100 * 80</gadget>
<output>32_000</output>

<gadget id="calculator">288_000 - 360_000 - 40_000 - 32_000</gadget>
<output>-144_000</output>

<gadget id="calculator">360_000 + (-144_000)</gadget>
<output>216_000</output>

<gadget id="calculator">4 * 100</gadget>
<output>400</output>

<gadget id="calculator">4 * 80</gadget>
<output>320</output>

<gadget id="calculator">3_600 + 400 + 320</gadget>
<output>4_320</output>

<gadget id="calculator">216_000 / 4_320</gadget>
<output>50</output>

<result>50</result>