A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is:
Rs. 650
Rs. 690
Rs. 698
Rs. 700
Explanation:
S.I. for 1 year = Rs. $\left(854 - 815\right)$ = Rs. 39.
S.I. for 3 years = Rs.$\left(39 \times 3\right)$ = Rs. 117.
$\therefore$ Principal = Rs. $\left(815 - 117\right)$ = Rs. 698.