A bear sleeps about 20 hours a day, a lion sleeps less than a bear (9/10), how many hours a lion sleeps a day.
熊每天的睡眠大约是20小时，狮子每天的睡眠时间比熊短(9/10)，狮子每天睡眠多少小时．
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">20 * (1/10)</gadget>
<output>2</output>

<result>2</result>