The number of boys in class one of six years accounts for 5/9 of the whole class, so the number of girls is the number of boys.
六年一班男生人数占全班人数的(5/9)，那么女生人数是男生人数的多少．
<gadget id="calculator">9 - 5</gadget>
<output>4</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>