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: of the final grades received by the students in a certain math course , 1 / 5 are a ' s , 1 / 4 are b ' s , 1 / 2 are c ' s , and the remaining 30 grades are d ' s . what is the number of students in the course ? 
Options: a ) 80 , b ) 110 , c ) 160 , d ) 600 , e ) 400

A: d
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Q: Problem: a seller of used cars has 16 cars to sell and each of his clients selected 2 cars that he liked most . if each car was selected exactly thrice , how many clients visited the garage ? 
Options: a ) 8 , b ) 10 , c ) 12 , d ) 14 , e ) 24

A: e
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Q: Problem: ( 4300331 ) - ? = 2535618 
Options: a ) 1865113 , b ) 1775123 , c ) 1764713 , d ) 1675123 , e ) none of them

A:
c
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