The number of the three classes of the fifth grade is equal, the number of boys in the first class is equal to the number of girls in the second class, and the number of boys in the third class is 2/5 of the total number of boys. Find the percentage of the total number of girls in the whole grade?
五年级三个班的人数相等，一班的男生人数与二班女生人数相等，三班的男生人数是全部男生人数的(2/5)，求全部女生人数占全年级的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 / (2/5)</gadget>
<output>50</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">50 * (3/5) * 3</gadget>
<output>90</output>

<gadget id="calculator">20 / (2/5) / 90</gadget>
<output>5/9 = around 0.555556</output>

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

<result>4/9 = around 0.444444</result>