2013 AIME I Problem 9

A paper equilateral triangle A B C has side length 12 . The paper triangle is folded so that vertex A touches a point on side \overline{B C} a distance 9 from point B. The length of the line segment along which the triangle is folded can be written as \frac{m \sqrt{p}}{n}, where m, n, and p are positive integers, m and n are relatively prime, and p is not divisible by the square of any prime. Find m+n+p.