a student reached his school late by 20mins by travelling at a speed of 9kmph.if he had travelled at a speed of 12kmph,he would have reached his school 20mins early.what is the distance between house and school? Choose the correct choice from the following options:
A) 24
B) 25
C) 26
D) 27
E) 28

Rationale: distance = distance either student reaches school before time or after time 9 ( t + 20 / 60 ) = 12 ( t - 20 / 60 ) i . e 9 ( t + 1 / 3 ) = 12 ( t - 1 / 3 ) 9 ( 3 t + 1 ) = 12 ( 3 t - 1 ) t = 7 / 3 put t value in any of distance equation put t = 7 / 3 in 9 ( t + 1 / 3 ) we get 24 km answer : a
Answer: A