The number of boys in class 51 is the number of girls (4/5), and the number of boys is the number of the whole class
五1班男生人数是女生人数的(4/5)，男生人数是全班人数的多少
<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>