A sum of money at simple interest amounts to Rs. 800 in 3 years and to Rs. 854 in 4 years. The sum is:  Choose the correct choice from the following choices
A) Rs. 438. B) Rs. 488. C) Rs. 518. D) Rs. 638. E) Rs. 664.
S.I. for 1 year = Rs. (854 - 800) = Rs. 54   S.I. for 3 years = Rs.(54 x 3) = Rs. 162.   Principal = Rs. (800 - 162) = Rs. 638.   ANSWER : Rs. 638.
<result>D</result>
A sum of money at simple interest amounts to Rs. 800 in 3 years and to Rs. 854 in 4 years. The sum is: