If the number of boys in Class 1 accounts for 4/9 of the whole class, then the number of girls is the number of boys.
六1班男生人数占全班人数的(4/9)，那么女生人数是男生人数的多少．
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (4/9)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">(5/9) / (4/9)</gadget>
<output>5/4 = around 1.25</output>

<result>5/4 = around 1.25</result>