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 store reported total sales of $ 460 million for february of this year . if the total sales for the same month last year was $ 320 million , approximately what was the percent increase in sales ? 
Options: a ) 2 % , b ) 17 % , c ) 44 % , d ) 65 % , e ) 83 %
c

Problem: the sum of ages of 5 children born at the intervals of 3 years each is 80 years . what is the age of the youngest child ? 
Options: a ) 3 years , b ) 4 years , c ) 6 years , d ) 7 years , e ) 10 years
e

Problem: a 6 - liter solution is 30 % alcohol . how many liters of pure alcohol must be added to produce a solution that is 50 % alcohol ? 
Options: a ) 1.8 , b ) 2.1 , c ) 2.4 , d ) 2.7 , e ) 3.0

c