The distance between (23,5) and (23,-12) is 17 units.
Because the x values are equal then this makes this problem much easier. Since y value 5 and y value -12 are in different quadrants then you would add them together (because one value is positive and one is negative). You need to add 5 and the absolute value of -12 which is 12. Adding 5 and 12 and you would get 17.