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: a is two years older than b who is twice as old as c . if the total of the ages of a , b and c be 12 , the how old is b ? 
Options: a ) 10 years , b ) 4 years , c ) 6 years , d ) 15 years , e ) 16 years
b

Problem: a mixture contains alcohol and water in the ratio 4 : 3 . if 8 litres of water is added to the mixture , the ratio becomes 4 : 5 . find the quantity of alcohol in the given mixture 
Options: a ) 15 litres , b ) 10 litres , c ) 30 litres , d ) 22 litres , e ) 16 litres
e

Problem: if doubling a number and adding 20 to the result gives the same answer as multiplying the number by 8 and taking away 4 from the product , the number is 
Options: a ) 2 , b ) 3 , c ) 4 , d ) 6 , e ) 7

c