The master and the apprentice work together to process a batch of parts. The original plan is that the ratio of the number of parts made by the master and the apprentice is 5:4. When the task is completed, the master made (2/3) of the total number, which is more than the original plan. 18 parts, how many parts did the apprentice originally plan to make?
师徒两人共同加工一批零件，原计划师徒两人所做零件个数的比为5：4，结果完成任务时，师傅做了总数的(2/3)，比原计划多做了18个零件，徒弟原计划做多少个零件？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">(2/3) - (5/9)</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">18 / (1/9)</gadget>
<output>162</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">162 * (4/9)</gadget>
<output>72</output>

<result>72</result>