#### Answer

a) Yes
b) Yes

#### Work Step by Step

a) Distance is always positive or zero, which means that we have to always take into consideration its absolute value. This means that the distance between any two different real numbers is always positive.
b) The formula to calculate distance is d(a, b) = | b - a |. If we had to calculate the distance between two numbers, -5 and 7, we would proceed in the following way:
d(a, b) = | b - a |
d(-5, 7) = | 7 - (-5) |
d(-5, 7) = | 7 + 5 |
d(-5, 7) = 12
If we were to use 7 as a and -5 as b, we would get the same result:
d(7, -5) = | -5 - 7 |
d(7, -5) = | - 12 |
| a | = - a if a