Final answer:
To find the temperature difference, subtract the temperature in Billings (-18°F) from the temperature in Mesa (42°F), resulting in a 60°F difference. Mesa was 60°F warmer than Billings.
Step-by-step explanation:
The question asks how much warmer it was in Mesa, Arizona compared to Billings, Montana, if at noon, it was -18°F in Billings and 42°F in Mesa. Calculating the difference in temperature between the two locations involves subtracting the lower temperature (Billings) from the higher temperature (Mesa).
42°F (Mesa) - (-18°F) (Billings) = 42°F + 18°F = 60°F.
Therefore, the answer is 60°F, which means Mesa was 60°F warmer than Billings.