Answer:
x=10
Explanation:
We can use the angle bisector theorem to solve this problem
8 12
-------- = ---------
x+4 2x+1
Using cross products
8(2x+1) = 12(x+4)
Distribute
16x+8 = 12x+48
Subtract 12x from each side
16x -12x +8 = 12x-12x +48
4x +8 = 48
Subtract 8 from each side
4x+8-8 = 48-8
4x = 40
4x/4 = 40/4
x=10