A sum at simple interests at 13 ½ % per annum amounts to Rs.2502.50 after 4 years find the sum.

Let sum be Rs. x then , S.I.=Rs.(x*(27/2) *4*(1/100) ) = Rs.27x/50

       amount = (Rs. x+(27x/50)) = Rs.77x/50

        77x/50 = 2502.50
       
        x =$\frac{2502.50*50}{77}$   = 1625                                                 

         Hence , sum = Rs.1625.