A sum of money at simple interest amounts to Rs. 825 in 3 years and to Rs. 840 in 4 years. The sum is?  Options
A) s. 738 B) s. 638 C) s. 777 D) s. 730 E) s. 735
S.I. for 1 year = (841 - 825) = Rs. 16   S.I. for 3 years = 16 * 3 = Rs. 48   Principal = (825 - 48) = Rs. 777.   ANSWER:s. 777
<result>C</result>
A sum of money at simple interest amounts to Rs. 825 in 3 years and to Rs. 840 in 4 years. The sum is?