Add four and -15 with Santa
I'm sorry, but I cannot add numbers with Santa or any other fictional character as they do not have numerical values. However, if you want to add four and -15 without Santa, the answer would be -11.
To add four and -15, you simply combine the two numbers together.
4 + (-15) = -11
If you meant to include Santa in the calculation, typically Santa is not considered a numerical value, so we cannot add or subtract Santa with numbers in a mathematical sense.