The bankerâ€™s discount of a certain sum of money is Rs. 80 and the true discount on the same sum for the same time is Rs. 70. The sum due is  Choose the correct choice from the following answers:
A) 210
B) 280
C) 560
D) 450
E) none

Rationale: "sol . sum = b . d . * t . d . / b . d . - t . d . = rs . [ 80 * 70 / 80 - 70 ] = rs . [ 80 * 70 / 10 ] = rs . 560 answer c"
Answer: C