Simple interest on a certain sum at the rate of 4.5% p.a. for 4 years and 6 years differs by BDT 216. The sum is-

Question: Simple interest on a certain sum at the rate of 4.5% p.a for 4 years and 6 years differs by BDT 216. The sum is-

Solution:
Let the sum be Tk. P
Simple interest, I = Pnr/100

ATQ,
216 = {(P × 4.5 × 6)​/100} - {(P × 4.5 × 4​)/100}
⇒ 216 = (27P - 18P)/100
⇒ 21600 = 9P
⇒ P = 21600/9
∴ P = 2400