A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is?  Choose one:	A) 287	B) 278	C) 698	D) 279	E) 275
S.I. for 1 year = (854 - 815)   = Rs. 39   S.I. for 3 years = 39 * 3   = Rs. 117   Principal = (815 - 117)   =Rs.698.   Answer: 698
<result>C</result>
A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is?