a) The distance between 4 and -24 on a number line.
A distance in one dimension can be calculated as:

b) The distance between -12 and 5 on a number line.

c) The distance between -14 and -6 on a number line.

Note: when calculating distances, it doesn't matter which of the two numbers we put first in the substracion. It will yield the same result.
Answer: A) 28, B) 17 C) 8