Among the students reading in the reading room, male students accounted for (5/9). After 4 male students walked out of the reading room, among the students reading books, female students accounted for (1/2). How many students were there in the original reading room? reading?
阅览室看书的学生中，男同学占了(5/9)，从阅览室走出4名男同学后，看书的学生中，女同学占(1/2)，原来阅览室一共有多少名学生在看书？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 * (1/2)</gadget>
<output>2</output>

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

<gadget id="calculator">(5/9) - 1</gadget>
<output>-4/9 = around -0.444444</output>

<gadget id="calculator">(1/2) + (-4/9)</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">2 / (1/18)</gadget>
<output>36</output>

<result>36</result>