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'.
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Question: 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

Answer: c


Question: Problem: what is the ratio of 3 / 7 to the product 2 * ( 7 / 3 ) ? 
Options: a ) 3 : 7 , b ) 9 : 98 , c ) 3 : 21 , d ) 1 : 7 , e ) 3 : 49

Answer: b


Question: Problem: the difference between the ages of two persons is 10 years . fifteen years ago , the elder one was twice as old as the younger one . the present age of the elder person is ? 
Options: a ) 35 yr , b ) 25 yr , c ) 20 yr , d ) 30 yr , e ) 40 yr

Answer:
a