Answer:
Option A) -20°F.
Explanation:
Given : It's was 55°F outside until the temperature increased 20°F.
To find : Which number is the additive inverse of the temperature increase?
Solution :
Additive inverse is defined as,
For any number 'a', the additive inverse is
or

According to question,
The temperature is increased 20°F.
To follow the additive inverse property,
The sum became zero.
So, Additive inverse is -20°F.
Therefore, Option A is correct.
The additive inverse of the temperature increase is -20°F.