Master Wang wants to process a batch of parts. The ratio of the number of parts he processes on the first day to the total number of parts in this batch is 3:8. If he processes 72 more parts, 60% of this batch of parts can be completed. How many parts are there in total?
王师傅要加工一批零件，他第一天加工的零件个数与这批零件总数的比是3：8，如果再加工72个零件就可以完成这批零件的60%．这批零件一共有多少个？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(3/5) - (3/8)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">72 / (9/40)</gadget>
<output>320</output>

<result>320</result>