White the abbreviations for fifteen degrees below zero

-15°

Step-by-step 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°