Among the students reading in the reading room, female students accounted for (3/5), and 5 female students left. Among the students reading at this time, female students accounted for (4/7). How many students were there in the original reading room?
阅览室看书的同学中，女同学占(3/5)，有5名女同学离开，这时看书的同学中，女同学占(4/7)．原来阅览室里一共有多少名同学？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">7 - 4</gadget>
<output>3</output>

<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">(3/2) - (4/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">5 / (1/6) / (2/5)</gadget>
<output>75</output>

<result>75</result>