A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 865 in 4 years. The sum is: Choose the correct choice:	A) s. 665	B) s. 690	C) s. 698	D) s. 700	E) s. 720
S.I. for 1 year = Rs. (865 - 815) = Rs. 50.   S.I. for 3 years = Rs.(50 x 3) = Rs. 150.   Principal = Rs. (815 - 150) = Rs. 665.   s. 665nswer: Option s. 665
<result>A</result>
A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 865 in 4 years. The sum is: