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: 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]: a


[Q]: Problem: if the average ( arithmetic mean ) of a and b is 110 , and the average of b and c is 170 , what is the value of a − c ? 
Options: a ) − 120 , b ) − 100 , c ) 100 , d ) 135 , e ) it can not be determined from the information given
[A]: a


[Q]: Problem: how many multiples of 10 are there between 10 and 290 ? 
Options: a ) 8 , b ) 18 , c ) 27 , d ) 51 , e ) 60
[A]:
c