If the highest temperature in a day in a certain place is 4**0C and the lowest temperature is -5**0C, what is the temperature difference in this day?
某地一天中最高的气温为4**0C，最低气温为-5**0C，则这一天的温度差为多少．
<gadget id="calculator">4 - (-5)</gadget>
<output>9</output>

<result>9</result>