+154 Each tick marks 60 units.
Samantha traveled two ticks to the right.
2 * 60 units = 120 units
Ryu traveled 8 ticks to the left.
(Negative values represent the distance traveled west, in this case to the left.)
-8 * 60 units = -480 units
Now there are two ways you can find the distance between them.
1) You can subtract their positions.
120 - (-480) = 120 + 480 = 600 units
2) Draw a picture.
As you can see from drawing the picture, the distance between them can be found by doing 480 + 120 = 600 units
