Answer:
-15°
Explanation:
When writing an abbreviation of any mathematical value below 0, the value will always have a negative(-) symbol. The symbol represents that it is a value that is below the value of 0.
On the other hand any value that is above 0 will not have the negative symbol with it.
Examples:
Five degrees below 0 = -5°
Five degrees above 0 = 5°