One morning the temperature is 6.5°C, the temperature at noon is 3.1°C higher than that in the morning, and at night it is 4.5°C lower than that at noon. What's the temperature tonight?
某天早上气温是6.5℃，中午气温比早上升高了3.1℃，晚上比中午降低了4.5℃．请问这天晚上的气温是多少？
<gadget id="calculator">3.1 - 4.5</gadget>
<output>-1.4</output>

<gadget id="calculator">6.5 + (-1.4)</gadget>
<output>5.1</output>

<result>5.1</result>