There are students in the auditorium. After 10 girls leave, the number of boys is twice that of girls. After another 9 girls leave, the number of boys is 4 times that of girls. How many students were there in the auditorium?
礼堂有学生，走了10名女生后，男生是女生的2倍，又走了9名女生后，男生是女生的4倍，礼堂里原来有多少名学生？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">36 - 20</gadget>
<output>16</output>

<gadget id="calculator">40 + 16</gadget>
<output>56</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">56 / 2</gadget>
<output>28</output>

<gadget id="calculator">28 - 10</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">28 + 36</gadget>
<output>64</output>

<result>64</result>