Integers, SM-Bank 031 MC

At midday the temperature is `-`3°C.

At 9pm the temperature is `-`12°C.

Which one of these calculations can be used to work out how many degrees warmer it is at midday than at 9 pm?

1. `-12 ÷ 3`
2. `-3+12`
3. `12+3`
4. ` -3-12`