If a certain toy store's revenue in November was 3/5 of its revenue in December and its revenue in January was 1/3 of its revenue in November, then the store's revenue in December was how many times the average (arithmetic mean) of its revenues in November and January?
Choose the correct answer:
A) 5 / 2  B) 7 / 2  C) 10 / 3  D) 15 / 4  E) 25 / 3

Rationale: "n = 3 d / 5 j = n / 3 = d / 5 the average of november and january is ( n + j ) / 2 = 4 d / 5 / 2 = 2 d / 5 d is 5 / 2 times the average of november and january . the answer is a ."
Answer: A