Table of figures, finding new revenue, very short but difficult brain teaser

http://img153.imageshack.us/img153/9184/capturep.jpg

Student discount price: $4

Normal price: $7

**Multiple Choice Question**: If the club offered no discount for students and consequently the number of students attending dropped by 10%, what would be the **new revenue** created for Jan?

Choice of answers:

A) $80,900

B) $92,000

C) $122,600

D) $104,000

Correct answer is D. I have been trying for hours to solve this problem!!

I have no idea how they got D.

This is what i've tried:

So, students have dropped by 10%. I assume they mean 10% per month. Therefore, for Jan we now have 0.9 * 14000 = 12600 student sales.

But we have 8000 "normal sales", who already pay full price ($7).

Therefore, the new revenue for Jan should be:

($7 * 8000) + ($7 * 12600) = $144,200

Now, I assume the answer they want doesn't take into account the "old" revenue, ie. the revenue that would already occur before taking away the discount anyway. This would be: ($7 * 8000) + ($4 * 14000) = $112,000

Therefore, the new revenue generated by the removal of the discount would be: $144200 - $112000 = $322,000.

But this isn't in the choice of answers! So how did they get choice D? Does anyone know? Thanks!