a. The absolute value of a number is the distance of the number from zero on a number line. It is always a non-negative value, meaning that it is either zero or a positive number. It is denoted by two vertical bars surrounding the number, like |x|.
b. The absolute value of -109 is the distance of -109 from zero on a number line. Since -109 is 109 units away from zero, the absolute value of -109 is 109. Therefore, |-109| = 109.
c. First, we need to evaluate |-7|, which is the absolute value of -7. The distance of -7 from zero on a number line is 7 units, so |-7| = 7. Therefore, the expression |-7| - 2 is equivalent to 7 - 2, which is equal to 5. Therefore, |-7| - 2 = 5.