Answer:
9 pieces of gum
Explanation:
The ratio is 3:5, so if I added 12 more pieces of candy, I would get ?:17. 17 divided by 5 is 3.4, but I round to 3 because you can't have half a piece of candy. Then I times the original amount of gum(3) and 3. That equals 9, so 9 pieces of gum keeps the ratio equivalent.