It takes 12 days for A and B to process a batch of parts; A works for 3 days and leaves due to something, and then B works for 2 days, leaving (4/5) of the batch of parts unfinished. It is known that A processes 4 less parts than B every day, how many parts are there in total?
加工一批零件，甲乙两人合作需12天完成；甲工作3天后因有事离开，然后由乙工作2天，还剩下这批零件的(4/5)没完成．已知甲每天比乙少加工4个，这批零件共有多少个？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/12) * 2</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/5) - (1/6)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">(1/30) / 1</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/12) - (1/30) - (1/30)</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">4 / (1/60)</gadget>
<output>240</output>

<result>240</result>