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: each of the products produced yesterday was checked by worker x or worker y . 0.5 % of the products checked by worker x are defective and 0.8 % of the products checked by worker y are defective . if the total defective rate of all the products checked by worker x and worker y is 0.7 % , what fraction of the products was checked by worker y ? 
Options: a ) 2 / 3 , b ) 5 / 6 , c ) 7 / 8 , d ) 4 / 5 , e ) 5 / 8
[A]: a


[Q]: Problem: for how many integer values of n will the value of the expression 4 n + 7 be an integer greater than 1 and less than 60 ? 
Options: a ) 10 , b ) 15 , c ) 8 , d ) 12 , e ) 20
[A]: b


[Q]: Problem: if a : b = 4 : 7 and b : c = 5 : 9 , then a : c = ? 
Options: a ) 28 : 37 , b ) 18 : 37 , c ) 16 : 53 , d ) 20 : 63 , e ) 15 : 48
[A]:
d