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: bert left the house with n dollars . he spent 1 / 4 of this at the hardware store , then $ 9 at the dry cleaners , and then half of what was left at the grocery store . when he got home , he had $ 12 left in his pocket . what was the value of n ? 
Options: a ) $ 36 , b ) $ 44 , c ) $ 52 , d ) $ 60 , e ) $ 68
[EX A]: b

[EX 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
[EX A]: d

[EX Q]: Problem: if the sum of the first n positive integers is s , what is the sum of the first n positive integers divisible by 3 , in terms of s ? 
Options: a ) s / 2 , b ) s , c ) 2 s , d ) 3 s , e ) 4 s
[EX A]:
d