On a certain day, the ratio of day to night in a certain place is 7:5, how many hours of night are there in that place on that day.
某一天中，某地白昼与黑夜的比是7：5，这天该地的黑夜有多少小时．
<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">24 * (5/12)</gadget>
<output>10</output>

<result>10</result>