A partnership made an average monthly profit of $15000$ over the year. At the midpoint of the year, D and E took on a new partner F, and profits were divided equally both before and after this change. In the first half of the year, D introduced his private vehicle into the partnership at a valuation of $12000$. D’s drawings totalled $60000$ for the year. By what amount did D’s current account balance increase over the year?
- A$15000$
- B$30000$
- C$75000$
- D$87000$