If the number of girls in a class is 4/5 of the number of boys, what is the percentage of boys in the whole class?
某班女生人数是男生人数的(4/5)，则男生人数占全班人数的多少．
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<result>5/9 = around 0.555556</result>