Question 1022013
I assume driven home.
Starting at (0,0), 
To the pharmacy,
(0,0)+(6,0)=(6,0)
To the pet shop,
(6,0)+(0,7)=(6,7)
To the dry cleaners,
(6,7)+(-5,0)=(1,7)
Back to home,
(1,7)+(X,Y)=(0,0)
X=-1. One block west,
Y=-7. Seven blocks south.
8 blocks total.