A sum lent out at simple interest amounts to Rs. 6076 in 1 year and 7504 in 4 years. The sum and the rate of interest per annum are respectively:

5600, 8.5%

Simple interest remains same after every year;

⇒ 3 years simple interest ⇒ 7504 - 6076 = 1428.

⇒ 1 year simple interest = $\frac{1428}{3}$ = 476

Therefore.

Principal ⇒ Amount (at the end of 1st year) - S.I. of 1 year

             ⇒ 6076 - 476 = Rs.5600

S.I. = $\frac{P × R × T}{100}$ 

⇒ 476 = $\frac{5600 × R × 1}{100}$

⇒ R = $\frac{476 }{56}$ = 8.5%