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: cost is expressed by the formula tb ^ 4 . if b is doubled , the new cost is what percent of the original cost ? 
Options: a ) 200 , b ) 600 , c ) 800 , d ) 1600 , e ) 50
[A]: d


[Q]: Problem: the sum of three consecutive multiples of 3 is 108 . what is the largest number ? 
Options: a ) 36 , b ) 39 , c ) 33 , d ) 30 , e ) 42
[A]: b


[Q]: Problem: how many different pairs of positive integers ( a , b ) satisfy the equation 1 / a + 1 / b = 34 / 51 ? 
Options: a ) 6 , b ) 3 , c ) 2 , d ) 1 , e ) 0
[A]:
e