Answer:
Step-by-step explanation:
Set up a ratio.
An angle bisector divides the side opposite it in the same ratio as the two sides defining the angle where the vertex and angle bisector meet.
14/6 = 21 / 3x - 12
Cross multiply
14(3x - 12) = 6*21
Remove the brackets
42x - 168 = 126
Add 168 to both sides
42x = 168 + 126
Combine
42x = 294
Divide by 42
x = 294/42
x = 7
