A brother and sister daily leave home together to go to their respective schools. The brother goes 3 km North, then turns left and goes 1 km to reach his school. The sister goes 4 km West, then 3 km North, then turns left and goes 5 km to reach her school. Where is the brother's school with respect to the sister's school?

Let the starting point (home) be (0,0).
Brother's path:

Goes 3 km North →(0,3)

Turns left (West) and goes 1 km →(−1,3)

Brother's school location: (−1,3)

Sister's path:

Goes 4 km West →(−4,0)

Goes 3 km North →(−4,3)

Turns left (West) and goes 5 km →(−4−5,3)=(−9,3)

Sister's school location: (−9,3)

Comparison:
Both schools are at the same latitude (y-coordinate =3).
Distance between brother's school and sister's school along the x-axis:

−1−(−9)=−1+9=8 km
Since the brother's coordinate (−1) is to the right of the sister's coordinate (−9), the brother's school is 8 km East with respect to the sister's school.