Instructions: 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'.
Input: Problem: if the arithmetic mean of p and q is 10 and the arithmetic mean of q and r is 24 , what is the value of r - p ? 
Options: a ) 28 , b ) 10 , c ) 30 , d ) 40 , e ) 5
Output:
a