If you multiply 23 by 12 you will get 276.
The answer for your question is a
No the side lengths of 9,12, and 18 doesn’t form a right triangle. Posted a picture showing all the side length that is a right triangle.
5 + 8 = 13
169/13 = 13
13 * 5 = 65
13 * 8 = 104
Thus, 65:104