Answer and explanation:
Let’s assume that the sum lent is P. The interest earned on this sum over 8 years at a 4% simple interest rate would be P * 4% * 8 = 0.32P. According to the information given, this interest is Rs 340 less than the sum lent, so 0.32P = P - 340. Solving this equation for P, we get P = 500. So, the sum lent was Rs 500.