The simple interest and the true discount on a certain sum for a given time and at a given rate are Rs. 88 and Rs. 80 respectively. The sum is:
Choose the correct choice
A) 880
B) 1450
C) 1600
D) 1800
E) none

Rationale: "sol . sum = s . i . * t . d . / ( s . i ) - ( t . d . ) = 88 * 80 / ( 88 - 80 ) = rs . 880 . answer a"
Answer: A