A supermarket operates 15 hours a day and closes at 11 pm. When does this supermarket open?
一家超市每天营业15小时，晚上11时休息．这家超市几时开始营业？
<gadget id="calculator">12 - 15</gadget>
<output>-3</output>

<gadget id="calculator">11 + (-3)</gadget>
<output>8</output>

<result>8</result>