A batch of parts is distributed to the master and the apprentice according to the ratio of 3:1. The efficiency ratio of the master and the apprentice is 5:3. After 5 hours of cooperation, (2/3) of the batch of parts is completed. At this time, the master There are still 400 parts unprocessed, how many parts are there in this batch?
把一批零件按3：1分给师、徒两人加工，师、徒两人的效率比是5：3，合作5小时后，共完成这批零件的(2/3)，这时师傅还有400个零件未加工，这批零件共有多少个？
<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(5/8) * (2/3)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(3/4) - (5/12)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">400 / (1/3)</gadget>
<output>1_200</output>

<result>1_200</result>