A sum amounts to

We have,

Where,

P is the principal (in Rs)

T is the time (in years)

R is the rate of interest (in % per annum)

Given: Amount = Rs. 3605

Time (T) = 219 days

Rate of interest (R) = 5% per annum

Let the sum (P) be Rs. x.

Here, we have T in days. So, we need to convert to years.

So,

We have Amount = Principal + Interest

⇒ 3605 = x + 0.03x

⇒ 1.03x = 3605

Thus, the sum is Rs. 3500.