The houses of five persons A, B, C, D and E are situated in such a way that A's house is 60 m to the north of E's house. D's house is 30 m to the west of E's house. B's house is 60 m to the north of C's house. C's house is 30 m to the west of D's house. In which direction is B's house with reference to A's house?