Chapter R - Section R.2 - Operations on Real Numbers - R.2 Exercises - Page 22: 122

(a) 6 (b) 9 (c) 16

We find the differences by looking at the distance between the numbers on a number line (see plot). (a) The difference, or distance, between $0$ and $6$ on the number line is 6. (b) The difference, or distance, between $-15$ and $-24$ on the number line is $9$. (c) The difference, or distance, between $-4$ and $-20$ on the number line is $16$.