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'.

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

Problem: mary ' s income is 60 % more than tim ' s income and tim ' s income is 10 % less than juan ' s income . what % of juan ' s income is mary ' s income . 
Options: a ) 144 % , b ) b . 120 % , c ) 96 % , d ) 80 % , e ) 64 %
a

Problem: 1 + 2 = 10 2 + 3 = 26 3 + 4 = 50 then 4 + 5 = ? 
Options: a ) 80 , b ) 81 , c ) 82 , d ) 83 , e ) 84

c