instruction:
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'.
question:
Problem: working simultaneously and independently at an identical constant rate , 5 machines of a certain type can produce a total of x units of product p in 4 days . how many of these machines , working simultaneously and independently at this constant rate , can produce a total of 2 x units of product p in 2 days ? 
Options: a ) 11 , b ) 13 , c ) 15 , d ) 18 , e ) 20
answer:
e


question:
Problem: exactly 3 / 5 of the people in the room are under the age of 21 , and exactly 5 / 13 of the people in the room are over the age of 65 . if the total number of the people in the room is greater than 50 and less than 100 , how many people in the room are under the age of 21 ? 
Options: a ) 21 , b ) 35 , c ) 39 , d ) 60 , e ) 42
answer:
e


question:
Problem: if ( 4 - x ) / ( 3 + x ) = x , what is the value of x ^ 2 + 4 x - 4 ? 
Options: a ) - 4 , b ) - 1 , c ) 0 , d ) 1 , e ) 4
answer:

c