In traveling from a dormitory to a certain city, a student went 1/2 of the way by foot, 1/4 of the way by bus, and the remaining 6 kilometers by car. What is the distance, in kilometers, from the dormitory to the city?
Pick:
A) 35	B) 24	C) 14	D) 24	E) 12

Rationale: "whole trip = distance by foot + distance by bus + distance by car x = 1 / 2 x + 1 / 4 x + 6 x - 1 / 2 x - 1 / 4 x = 6 x = 24 km option : d"
Answer: D