A workshop produces a batch of parts, and 40% of this batch of parts is produced in 4 hours. According to this calculation, 30 parts can be produced in 2.5 hours. How many parts are there in this batch?
某车间生产一批零件，4小时生产了这批零件的40%，照这样计算，2.5小时可生产30个，这批零件共有多少个？
<gadget id="calculator">30 / 2.5</gadget>
<output>12</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 / (2/5)</gadget>
<output>10</output>

<gadget id="calculator">12 * 10</gadget>
<output>120</output>

<result>120</result>