Cady A--75pieces
Candy B--175 pieces
Candy C--325 pieces
75=5x5x3
175=5x5x7
325=5x5x13
As we can see the highest common factor is 5x5=25
So,
The number of bags that Bonnie can make so that each one has the same number of candies is 25
Now,
Number of candies from bag A of the treat bag=3
Number of candies from bag B of the treat bag=7
Number of candies from bag C of the treat bag=1