Tk. 9800 are invested partly in 9% stock at 75 and 10% stock at 80 to have an equal amount of income. The investment in 9% stock is

Question: Tk. 9800 are invested partly in 9% stock at 75 and 10% stock at 80 to have an equal amount of income. The investment in 9% stock is:

Solution:
Let,
the investment in 9% stock be tk. x.
Then, investment in 10% stock = tk.(9800 - x)

According to the question,
(9/75) × x = (10/80) × (9800 - x)
⇒ 3x/25 = (9800 - x)/8
⇒ 24x = (9800 × 25) - 25x
⇒ 24x + 25x = 245000
⇒ 49x = 245000
⇒ x = 245000/49
∴ x = 5000