There are two classes in the fifth grade. The number of people in the first class (2/15) is transferred to the second class. At this time, the number of people in the second class (3/5) is (3/4) of the number of people in the first class. What percentage of the number of grades?
五年级有两个班，把一班人数的(2/15)调入二班，这时二班人数的(3/5)是一班人数的(3/4)，原来一班人数是全年级人数的几分之几？
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

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

<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">1 - (2/15)</gadget>
<output>13/15 = around 0.866667</output>

<gadget id="calculator">(4/9) / (13/15)</gadget>
<output>20/39 = around 0.512821</output>

<result>20/39 = around 0.512821</result>