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A person lent a certain sum of money at 4% per annum at simple interest and in a certain number of years the interest amounted to Rs. 306 less than the sum lent. The sum lent was Rs. 450. How many years did it take for the interest to amount to Rs. 306 less than the sum lent?
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Let's denote the sum lent as P, the rate of interest as R, the time in years as T, and the interest as I.

Given:
P = Rs. 450
R = 4% per annum
I = P - Rs. 306 (since the interest is Rs. 306 less than the sum lent)

The formula for simple interest is:
I = P * R * T / 100

Substituting the given values into the formula, we get:
P - 306 = (450 * 4 * T) / 100

Now, let's solve for T:
450 - 306 = (450 * 4 * T) / 100
144 = (450 * 4 * T) / 100
144 = 18 * T
T = 144 / 18
T = 8

Therefore, it took 8 years for the interest to amount to Rs. 306 less than the sum lent.
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