Detailed Instructions: In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Problem:Problem: 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 : 
Options: a ) 880 , b ) 1450 , c ) 1600 , d ) 1800 , e ) none
Solution:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
a