Answer :
Bobby has the most pencils. You have to convert all of the fractions so they have the same number in the denominator. To do this you have to find the lowest common multiple (LCM) for this question, all of the denominators have the number 24 in common. If you divide 24 by 6 you get 4 then you have to multiply 4 by the numerator to make sure that the fraction is being fully converted. You will get (8/24). Apply this to all three fractions and you will get (8/24), (16/24), (12/24). 16 is the largest number therefore bobby would have the most pencils. To check this you can simplify all of the fractions back down. Do 8/24 and you will get .33333. If you do 2/6 then you get .33333, they are the same number which means you converted correctly and you have the right answer. Hope this helps!
According to my calculations, 4/12 of Mina's pencils are red, 8/12 of Bobby's pencils are red, and 6/12 of Julia's pencils are red. Therefore leaving Bobby with the most red pencils.