In the case of an equilateral triangle ABC, each angle measures 60 degrees, as the total angle sum in any triangle is 180 degrees, and dividing that by 3 yields 60. Setting this equal to 3x-12, we have 60 = 3x - 12. After adding 12 to both sides, we get 72 = 3x, and dividing 72 by 3 gives us x = 24.66! I hope this clarifies things for you!
Answer: 13
I made an error on the question, and it provided the right answer. Thank me later.