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: 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
[EX A]: a

[EX Q]: Problem: when toys are grouped into 12 and 18 , always 3 toys remain ungrouped . what is the minimum number of toys to be added so that when they are grouped into 7 , no toys will remain ungrouped ? 
Options: a ) 0 , b ) 1 , c ) 2 , d ) 3 , e ) 4
[EX A]: d

[EX Q]: Problem: in a certain company , the ratio of male to female employees is 7 : 8 . if 3 more men were hired , this ratio would increase to 8 : 9 . how many male employees are there in the company ? 
Options: a ) 6 , b ) 21 , c ) 27 , d ) 189 , e ) 192
[EX A]:
d