Answer
The change in velocity is 27 m/s in the west direction.
Work Step by Step
Let the east direction be the positive direction and let the west direction be the negative direction.
$v_1 = 12~m/s$
$v_2 = -15~m/s$
We can find the change in velocity:
$\Delta v = v_2-v_1 = -15~m/s-12~m/s = -27~m/s$
The change in velocity is 27 m/s in the west direction.
