The simple interest on a sum for a certain number of years is same as sum itself while the rate is same as the number of years for which it is invested. The number of years is equal to :

5 10 8 1

10

ATQ, Let Simple interest = Sum = S Let Rate = Time = Y By using formula , Simple Interest = \(\frac{Principal ×Rate × Time }{100}\) S = \(\frac{S ×Y × Y }{100}\) Y² = 100 Y = 10 years