Masood invests a part of Rs. 12000 in 12% stock at Rs. 120 and the remainder in 15% stock at Rs. 125. If his total dividend per annum is Rs. 1360, how much does he invest in 12% stock at Rs. 120?

A. Rs. 4500
B. Rs. 6000
C. Rs. 5500
D. Rs 4000

Let investment in 12% stock is Rs. x.
investment in 15% stock Rs. (12000 – x).

(12/120) * x + 15/125(12000-x) = 1360

5x + 72000 -6x hence x = 4000