The simple interest and the true discount on a certain sum for a given time and at a given rate are Rs. 85 and Rs. 78 respectively. The sum is: Choose the correct choice from the following choices:	A) 1360	B) 1450	C) 1600	D) 947	E) none

Rationale: sol . sum = s . i . * t . d . / ( s . i ) - ( t . d . ) = 85 * 78 / ( 85 - 78 ) = rs . 947 . answer d
Answer: D