In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: the difference between a 7 digit number and the number formed by reversing its digit is not a multiple of 
Options: a ) 121 , b ) 11 , c ) 9 , d ) 10 , e ) 3
[EX A]: a

[EX Q]: Problem: a number whose fifth part increased by 7 is equal to its fourth part diminished by 7 is ? 
Options: a ) 160 , b ) 180 , c ) 200 , d ) 280 , e ) none
[EX A]: d

[EX Q]: Problem: a sum of money lent out at s . i . amounts to a total of $ 590 after 2 years and to $ 815 after a further period of 5 years . what was the initial sum of money that was invested ? 
Options: a ) $ 490 , b ) $ 500 , c ) $ 510 , d ) $ 520 , e ) $ 530
[EX A]:
b