Problem Solving

Revenues were recorded for Store A and Store B over a period of three months. In the first month, Store A's revenues were $40,000 higher than Store B's revenues. In the second month, Store A's revenues were $8,000 higher than Store B's revenues. If Store A's average (arithmetic mean) monthly revenue for the three months was $2,000 greater than Store B's average monthly revenue, then Store B's revenue in the third month was how much greater than Store A's revenue?

(A) $14,000
(B) $15,000
(C) $42,000
(D) $46,000
(E) $50,000

OA is C.

Source: GMAT Hacks