Workshop A and Workshop B produce the same kind of parts, if the production task is allocated to workshop A and B according to 4:1, the two workshops can complete the task at the same time. In actual production, workshop B produces 15 parts per day, and because workshop A transfers some workers to complete other tasks, it actually produces 50 parts per day. A few days later, workshop B completed the task, and workshop A still had a part to complete. At this time, workshop A and B cooperated to complete the task in 2 days. Q: How many parts are there in this batch?
甲、乙两车间生产同一种零件，若按4：1向甲乙车间分配生产任务，这两个车间能同时完成任务．实际生产时，乙车间每天生产15个零件，由于甲车间抽调一部分工人去完成另外的任务，实际每天生产50个零件．若干天后，乙车间完成了任务，甲车间还剩一部分未完成，这时，甲乙两车间合作，2天后全部完成．问：这批零件有多少个？
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<gadget id="calculator">60 + 15</gadget>
<output>75</output>

<gadget id="calculator">50 + 15</gadget>
<output>65</output>

<gadget id="calculator">60 - 50</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">65 * (1/5)</gadget>
<output>13</output>

<gadget id="calculator">75 * 13</gadget>
<output>975</output>

<result>975</result>