Three workshops process a batch of parts, workshop A processes 300 pieces, workshop B processes 20% of these parts, workshop C processes the sum of workshops A and B, and the task is just completed at this time. How many parts are in this batch?
三个车间加工一批零件，甲车间加工300个，乙车间加工了这批零件的20%，丙车间加工的是甲乙两车间的和，这时正好完成任务．这批零件多少个？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5) - (1/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">2 / (3/5)</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">300 * (10/3)</gadget>
<output>1_000</output>

<result>1_000</result>