First find 15% of 12 by multiplying it by 0.15 to get 1.8. Since the question says "select all that apply," we can assume that there will be multiple answers to this, also since the ribbon can be too long or too short. Add 1.8 to 12 and subtract 1.8 from 12 to get 13.8 and 10.2, which is A and C. Hope this helps!
