Hello there!
You're given the value of -109.3°F, and you are told that is 184.9°F less than the outside temperature. To find the outside temperature, add the difference to the temperature of dry ice.
-109.3°F + 184.9°F =75.6°F
So, the outside temperature is 75.6°F. I hope this was helpful, have a great rest of your day!