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'.

[EX Q]: Problem: each year for 4 years , a farmer increased the number of trees in a certain orchard by 1 / 4 of the number of trees in the orchard of the preceding year . if all of the trees thrived and there were 12500 trees in the orchard at the end of 4 year period , how many trees were in the orchard at the beginning of the 4 year period . 
Options: a ) 5113 , b ) 5117 , c ) 5120 , d ) 8119 , e ) 10115
[EX A]: c

[EX Q]: Problem: the average age of a group of 10 persons was decreased by 3 years when one person , whose age was 42 years , was replaced by a new person . find the age of the new person ? 
Options: a ) 22 , b ) 18 , c ) 12 , d ) 88 , e ) 66
[EX A]: c

[EX Q]: Problem: for all numbers a and b , the operationis defined by ab = ( a + 2 ) ( b – 3 ) . if 3 x = – 25 , then x = 
Options: a ) – 15 , b ) – 2 , c ) - 3 , d ) 6 , e ) 15
[EX A]:
b