Use the Information Given Below (As at 30 June 2012)

Use the information given below (as at 30 June 2012) to answer the following questions:
$$\begin{array} { l r } &\$\\\text { Share capital } & 100000 \\\text { Equipment } & 150000 \\\text { Inventory } & 30000 \\\text { Accounts receivable } & 20000 \\\text { Accounts payable } & 30000 \\\text { Retained profits } & 80000 \\\text { Cash } & 10000\end{array}$$
Assume no dividends were declared during the year.
-If the balance of retained profits at the start of the year was $50 000,what was the profit for the year?

A) $30 000
B) $80 000
C) $50 000
D) $40 000.