Divide a batch of parts into two parts and give them to A and B to process separately. A can process 60 parts per hour, and B can complete the parts he wants to process in 10 hours. After B processes for half an hour, A can start processing. When B has processed (4/5) of all its parts, the ratio of A's processed parts to unprocessed parts is 5:1. How many parts are there in this batch?
把一批零件平均分成两部分交给甲、乙二人分别加工，甲每小时能加工零件60个，乙用10小时能完成自己要加工的零件，乙加工半小时后，甲才开始加工，当乙加工了自己全部零件的(4/5)时，甲已经加工的与未加工的零件数的比是5：1，这批零件有多少个？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">10 * (4/5)</gadget>
<output>8</output>

<gadget id="calculator">8 - 0.5</gadget>
<output>7.5</output>

<gadget id="calculator">1 + 5</gadget>
<output>6</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">7.5 / (5/6)</gadget>
<output>9</output>

<gadget id="calculator">9 * 60 * 2</gadget>
<output>1_080</output>

<result>1_080</result>