It costs 10¢ a kilometer to fly and 12¢ a kilometer to drive. If you

An alternate approach would be to model the question, if you don't know how to set up the algebra.

Pick an easy number for x, that is not an exact split (e.g. 100) or a number from the problem, such as 50.

If x = 50, then it costs 50 x .10 = $5 for the flight portion of the trip.

Then, there are 200 - 50 = 150 kilometers left for the drive portion of the trip, so it costs 150 x .12 = $18 for the drive portion of the trip.

Add the two values to find that when x = 50, the cost of the trip is $23. Now, eliminate choices A and B, which are defined numeric values that do not equal $23.

Then, plug in x = 50 into the remaining choices seeking one that yields $23.

(C) 24 - 2(50) = -76 ; eliminate choice C
(D) 24 - .02(50) = 23 ; keep choice D
(E) 2,400 - 2x = 2,300 ; eliminate choice E

The correct answer is choice D.

Since x kilometers represents the flying distance, (200 - x) kilometers represents the driving distance.

Thus, the cost was:

0.10x + 0.12(200 - x) = 0.10x + 24 - 0.12x = 24 - 0.02x

Answer: D

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.