The most reasonable ratio of children's daily activity and sleep time is 5:3. In this case, how many hours should children sleep a day?
儿童一天中活动与睡眠时间的比是5：3最合理，这样的话，儿童一天的睡眠时间应该是多少小时？
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

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

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

<result>9</result>