The temperature started at -12 degrees then increases by 8 degrees. This means that you can make an expression to solve this like so...
-12 + 8
When adding a positive number with a negative number you will act as if you are subtracting the two numbers, then take the sign of the largest number. In this case the largest number is 12 and its sign is negative. Your answer will have a negative sign.
Act as if you are subtracting...
12 - 8 = 4
Take the sign of the largest number (12)
-4 (third option)<<<This is the temperature now.
Hope this helped!
~Just a girl in love with Shawn Mendes