A and B can work together to process a batch of parts in 12 days. If A makes 4 days and B makes 40% of this batch of parts in 5 days, it is known that B processes 120 parts every day, how many parts are there in this batch?
甲、乙二人合做加工一批零件12天能完成．如果甲做4天，乙做5天共完成这批零件的40%，已知乙每天加工120个，这批零件一共有多少个？
<gadget id="calculator">5 * 120</gadget>
<output>600</output>

<gadget id="calculator">12 * 120 * 0.4</gadget>
<output>576</output>

<gadget id="calculator">600 - 576</gadget>
<output>24</output>

<gadget id="calculator">12 * 0.4</gadget>
<output>4.8</output>

<gadget id="calculator">4.8 - 4</gadget>
<output>0.8</output>

<gadget id="calculator">24 / 0.8</gadget>
<output>30</output>

<gadget id="calculator">120 + 30</gadget>
<output>150</output>

<gadget id="calculator">150 * 12</gadget>
<output>1_800</output>

<result>1_800</result>