Answer:
12:15 is NOT proportional to 3:4
Explanation:
7.5:10 is proportional to 3:4 because 3×2.5=7.5, and 4×2.5=10.
39:52 is proportional to 3:4 because 3×13=39, and 4×13=52
45:60 is proportional to 3:4 because 3x15=45, and 4×15=60
12:15 is not proportional to 3:4 because while you can multiply 3x4=12, you can not multiply 4×4 to get 15, you get 16 instead.