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: when 1 / 20 % of 4,000 is subtracted from 1 / 10 of 4,000 , the difference is 
Options: a ) 50 , b ) 200 , c ) 380 , d ) 398 , e ) 400
[A]: d


[Q]: Problem: the price of a bushel of corn is currently $ 3.20 , and the price of a peck of wheat is $ 8.80 . the price of corn is increasing at a constant rate of 5 x cents per day while the price of wheat is decreasing at a constant rate of x ( 2 ^ 1 / 2 ) - x cents per day . what is the approximate price when a bushel of corn costs the same amount as a peck of wheat ? 
Options: a ) $ 8.40 , b ) $ 5.10 , c ) $ 5.30 , d ) $ 5.50 , e ) $ 5.60
[A]: a


[Q]: Problem: find the maximum value of the function f ( x ) = x − 5 if x is a number between - 5 and 13 . 
Options: a ) 6 , b ) 7 , c ) 8 , d ) 9 , e ) none
[A]:
c