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: if ( a - b - c + d = 13 ) and ( a + b - c - d = 9 ) , what is the value of ( b - d ) ^ 2 ?
Options: a ) 4 . , b ) 8 . , c ) 12 . , d ) 16 . , e ) 64 .
a

Problem: by how much is 12 % of 24.2 more than 10 % of 14.2 ?
Options: a ) 0.1484 , b ) 14.84 , c ) 1.484 , d ) 2.762 , e ) none
c

Problem: 65 % of x = 20 % of 747.50 . find the value of x ?
Options: a ) 100 , b ) 230 , c ) 150 , d ) 180 , e ) 199
b