A boy is traveling from his house to school at 10km/hr and reached school 2hours late. Next day he traveled 20km/hr and reached 1hour early. Then find the distance between house and school?
Choose the correct choice from the following answers
A) 50 km	B) 45 km	C) 33 km	D) 60 km	E) 54 km

Rationale: let distance be x s 1 = 10 km / hr s 2 = 20 km / hr t 1 = x / 10 hr t 2 = x / 20 hr difference in time = 2 + 1 = 3 hr ( x / 10 ) - ( x / 20 ) = 3 x = 60 km answer is d
Answer: D