Master Zhang made 40% of the total number of parts on the first day. If he made 12 more parts, he would complete (2/3) of the total number. How many parts were made on the first day?
张师傅做一批零件，第一天做了总数的40%，如果再做12个，恰好完成总数的(2/3)，第一天做了多少个？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">(2/3) - (2/5)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">12 / (4/15)</gadget>
<output>45</output>

<gadget id="calculator">45 * (2/5)</gadget>
<output>18</output>

<result>18</result>