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 retailer bought a hat at wholesale and marked it up 60 % to its initial price of $ 24 . by how many more dollars does he need to increase the price to achieve a 100 % markup ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
d

Problem: if 7 a - 3 b = 10 b + 50 = - 12 b - 2 a , what is the value of 9 a + 9 b ? 
Options: a ) - 9 , b ) - 6 , c ) 0 , d ) 6 , e ) 9
c

Problem: if m and n are positive integer , and 1800 m = n ^ 3 , what is the least possible value of m ? 
Options: a ) 2 , b ) 3 , c ) 15 , d ) 30 , e ) 45

c