9514 1404 393
Answer:
x = 7
Step-by-step explanation:
The angle bisector divides the sides proportionally.
(3x -12)/6 = 21/14
3x -12 = 9 . . . . . . . multiply by 6 and simplify
x -4 = 3 . . . . . . . . divide by 3
x = 7 . . . . . . . . . . . add 4
