A sum of money invested at simple interest amounts to Rs 2480 at the end of four years and Rs.4080 at the end of eight years. Find the principal.
Rs.2040
Rs.1600
Rs.1240
Rs.880
Rs. 1480
Amount after 4 years = Rs 2480
Amount after 8 years = Rs 4080
Difference = 1600
Because interest is S.I , so it is equal for every year
P = A – I
2480 – 1600 = 880