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'.

[Q]: Problem: a sum of money lent out at s . i . amounts to a total of $ 480 after 2 years and to $ 680 after a further period of 5 years . what was the initial sum of money that was invested ? 
Options: a ) $ 360 , b ) $ 380 , c ) $ 400 , d ) $ 420 , e ) $ 440
[A]: c


[Q]: Problem: a envelop weight 8.5 gm , if 820 of these envelop are sent with an advertisement mail . how much wieght ? 
Options: a ) 6.6 kg , b ) 6.8 kg , c ) 6.7 kg , d ) 6.97 kg , e ) 7.8 kg
[A]: d


[Q]: Problem: a test has 150 questions . each question has 5 options , but only 1 option is correct . if test - takers mark the correct option , they are awarded 1 point . however , if an answer is incorrectly marked , the test - taker loses 0.25 points . no points are awarded or deducted if a question is not attempted . a certain group of test - takers attempted different numbers of questions , but each test - taker still received the same net score of 40 . what is the maximum possible number of such test - takers ? 
Options: a ) 19 , b ) 21 , c ) 23 , d ) 25 , e ) 27
[A]:
c