The number of students in a class is between 20 and 30, the ratio of the number of boys to girls is 3:5, how many fewer boys than girls.
某班学生人数在20人到30人之间，男、女生人数的比是3：5，男生比女生少多少人．
<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">24 * (5/8)</gadget>
<output>15</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">24 * (3/8)</gadget>
<output>9</output>

<gadget id="calculator">15 - 9</gadget>
<output>6</output>

<result>6</result>