A firm is comprised of partners and associates in a ratio of 2:63. If 45 more associates were hired, the ratio of partners to associates would be 1:34. How many partners are currently in the firm?  Pick:
A) 12  B) 14  C) 16  D) 18  E) 20

Rationale: "the ratio 1 : 34 = 2 : 68 so the ratio changed from 2 : 63 to 2 : 68 . 68 - 63 = 5 which is 1 / 9 of the increase in 45 associates . the ratio changed from 18 : 567 to 18 : 612 . thus the number of partners is 18 . the answer is d ."
Answer: D