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: a club wants to mix 20 pounds of candy worth $ 8.00 per pound with candy worth $ 5.00 per pound to reduce the cost of the mixture to $ 6.00 per pound . how many pounds of the $ 5.00 per pound candy should be used ? 
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60
[EX A]: c

[EX Q]: Problem: if 45 - [ 28 - { 37 - ( 15 - * ) } ] = 59 , then * is equal to : 
Options: a ) - 29 , b ) - 19 , c ) 20 , d ) 29 , e ) 39
[EX A]: c

[EX Q]: Problem: ( 3 x + 2 ) ( 2 x - 1 ) = ax ^ 2 + kx + n . what is the value of a - n + k ? 
Options: a ) 5 , b ) 8 , c ) 9 , d ) 10 , e ) 11
[EX A]:
c