A sum of 12,000 Taka is lent out in two parts. One part is lent at 8% simple interest and the other at 10% simple interest. If the total annual interest is 1,080 Taka, how much is lent at 8%?

Question: A sum of 12,000 Taka is lent out in two parts. One part is lent at 8% simple interest and the other at 10% simple interest. If the total annual interest is 1,080 Taka, how much is lent at 8%?

Solution:
Let,
Amount lent at 8% simple interest = x
Amount lent at 10% simple interest = (12000 - x)

We know,
I = Pnr
I = Pr [Since the time is 1 year]

Interest from the amount lent at 8%,
I = x(8/100) = 0.08x

Interest from the amount lent at 10%,
I = (12000 - x) × (10/100) = 0.10(12,000−x)

ATQ,
0.08x + 0.10(12,000−x) = 1080
⇒ 0.02x = 120
∴ x = 6000 Taka

So, Amount lent at 8% simple interest = 6000 Taka