In traveling from a dormitory to a certain city, a student went 1/4 of the way by foot, 1/2 of the way by bus, and the remaining 10 kilometers by car. What is the distance, in kilometers, from the dormitory to the city?  Answers:	A) 10	B) 45	C) 30	D) 20	E) 40

Rationale: "whole trip = distance by foot + distance by bus + distance by car x = 1 / 4 x + 1 / 2 x + 10 x - 1 / 4 x - 1 / 2 x = 10 x = 40 km option : e"
Answer: E