X amount of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. What is the value of X?
Rs. 698
S.I. for 1 year = Rs. (854 - 815) = Rs. 39
S.I. for 3 years = Rs. (39 x 3) = Rs. 117
So, Principal = Rs. (815 - 117) = Rs. 698