Answer
$d(P, Q)=3$
Work Step by Step
RECALL:
The distance between the points P and Q on a number line, whose coordinates are p and q, respectively, is given by the formula:
$d(P, Q) = |p-q| \text{ or } d(P, Q) = |q-p|$
Use the formula above to obtain:
$d(P, Q)
\\= |-1-(-4)|
\\= |-1+4|
\\= |-3|
\\= 3$
