On a certain day in Beijing, the highest temperature during the day is 6°C, and the lowest temperature drops to -3°C at night. What is the difference between the highest temperature and the lowest temperature in °C?
北京某一天白天的最高气温是6℃，夜晚最低降至-3℃，最高气温和最低气温相差多少℃
<gadget id="calculator">6 - (-3)</gadget>
<output>9</output>

<result>9</result>