To find the temperature difference between the room and the deep freezer, you simply subtract the temperature inside the deep freezer from the room temperature:
Temperature difference = Room temperature - Deep freezer temperature
Temperature difference = 24°C - (-3°C)
To subtract a negative number, you can change it to addition:
Temperature difference = 24°C + 3°C
Temperature difference = 27°C
So, the temperature difference between the room and the deep freezer is 27 degrees Celsius.