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'.

Problem: marcella has 27 pairs of shoes . if she loses 9 individual shoes , what is the greatest number of matching pairs she could have left ? 
Options: a ) 22 , b ) 20 , c ) 19 , d ) 16 , e ) 15
a

Problem: the population of a bacteria culture doubles every 2 minutes . approximately how many minutes will it take for the population to grow from 1,000 to 100,000 bacteria 
Options: a ) 10 , b ) 12 , c ) 14 , d ) 16 , e ) 18
c

Problem: a number when multiplied by 3 is odd and divisible by 9 . this number when multiplied by 4 is 108 . what is the original number ? 
Options: a ) 10 , b ) 18 , c ) 13 , d ) 21 , e ) 27

e