Two different triangles for player 1 and player 2
Both triangles have right angle and same angle where they are connected. So other angle is also same.
All angles are same so they are similar triangles.
smaller triangle is similar to larger triangle
Hence the sides are in proportion

So x * 9 = 12 * 8
9x = 96
Divide by 9 on both sides
x = 10.67 ft