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: 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
[EX A]: d

[EX Q]: Problem: find the principle on a certain sum of money at 5 % per annum for 3 1 / 5 years if the amount being rs . 580 ?
Options: a ) rs . 500 , b ) rs . 5100 , c ) rs . 530 , d ) rs . 540 , e ) none of these
[EX A]: a

[EX Q]: Problem: when positive integer n is divided by positive integer j , the remainder is 8 . if n / j = 150.25 , what is value of j ?
Options: a ) 16 , b ) 26 , c ) 32 , d ) 132 , e ) 20
[EX A]:
c