Two people, A and B, run in the same direction at the same time by a pool with a circumference of 400 meters. A runs at 120 m/min, and B runs at 100 m/min. A and B rest for 1 minute every time they run 200 meters. How many minutes does it take for A to catch up with B?
甲乙两人分别在周长为400米的水池边同时同向跑步，甲120米/分钟，乙100米/分钟，甲乙每跑200米休息1分钟，问甲经过多少分钟追上乙？
<gadget id="calculator">120 - 100</gadget>
<output>20</output>

<gadget id="calculator">400 / 20</gadget>
<output>20</output>

<gadget id="calculator">100 / 200</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 * (1/2)</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 * 1</gadget>
<output>9</output>

<gadget id="calculator">20 + 9</gadget>
<output>29</output>

<result>29</result>