If the number of boys is 4/5 of the number of girls, then how many boys account for the total number of students in the class?
男生人数是女生人数的(4/5)，那么男生人数占全班总人数的多少．
<gadget id="calculator">4 + 5</gadget>
<output>9</output>

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

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