A man bought some oranges at Rs.10 per dozen and bought the same number of oranges at Rs.8 per dozen. He sold these oranges at Rs.11 per dozen and gained Rs.120. The total number of oranges bought by him was?

Let the man bought 'b' dozens of oranges at Rs 10 per dozen.

CP$$_1$$ = 10a

He also bought the same number, i.e., 'b' dozens, of oranges at Rs 8 per dozen.

CP$$_2$$ = 8a

Total CP = 10a + 8a = 18a

Now he sold all the oranges at Rs 11 per dozen.

Total SP = 11 $$\times$$ 2a = 22a

Profit = Total SP - Total CP = 22a - 18a = 4a

$$\therefore$$ 4a = 120 $$\Rightarrow$$ a = 30

Total oranges bought = 2a dozens = 60 dozens

Hence, option D is the correct choice