It takes 20 days for A to process a batch of parts, and 30 days for B to complete it alone. Now after 2 days of cooperation between the two, there are still 2,500 parts that have not been processed. How many parts has B processed within the cooperation time?
加工一批零件，甲独做需要20天，乙独做需要30天完成，现在两人合作2天后，还剩下2500个零件没加工完成，问在合作时间内乙加工了多个零件？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 2</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 2</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 - (1/10) - (1/15)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">2_500 / (5/6)</gadget>
<output>3_000</output>

<gadget id="calculator">3_000 / 30</gadget>
<output>100</output>

<gadget id="calculator">100 * 2</gadget>
<output>200</output>

<result>200</result>