Chapter P, Prerequisites - Section P.2 - Real Numbers - P.2 Exercises - Page 15: 8

(a) Yes (b) Yes

(a) Yes. The "distance" between two real numbers can be thought of as the absolute value of their difference ($|a-b|$). Since absolute value is always positive, the distance will be positive. (b) Yes, using absolute values: $|a-b|=|-(b-a)|=|b-a|$