Let the distance between his school and house be d km. Time taken by the boy to go from his house to school + Time taken by the boy to go from his school to house = 50 minutes ∴
d
12
+
d
8
=
50
60
(Time=
Distance
Speed
) ⇒
5d
24
=
5
6
⇒d=4km Therefore, total distance walked by the boy = 2d = 8 km