Distance on number line question, please explain

Test Preparation
1

<p>On the number line, the distance between the point whose coordinate is a and the point whose coordinate is b is greater than 100. Which of the following must be true?
I. a-b>100
II. la-bl >100
III. lal.lbl >100</p>

<p>a. II only
b. III only
c. I and II only
d. II and III only
e. I, II and III</p>

<p>One daughter "gets it", one doesn't and cannot understand her sister's explanation- trying to have second daughter understand for future problems, not just for this one. Thank you in advance.</p>

2

<p>Only II is correct…the distance between any two points x and y is |x-y|.</p>

<p>I is clearly false (we can let a = -101, b = 0, a-b = -101). III is also false by this counterexample.</p>

3

<p>Using real numbers always helps but be sure to use positive AND negative numbers</p>