Answer:
x = 9
Step-by-step explanation:
Vertical angles are congruent, so their measures are equal.
4x + 6 = 7x - 21
Subtract 7x from both sides.
-3x + 6 = -21
Subtract 6 from both sides.
-3x = -27
Divide both sides by -3.
Because of the postulate "Vertical angles are equal" we can write the equation:
Then solve:
(4x + 6) + 21 = (7x - 21) + 21
(4x + 27) - 4x = (7x) - 4x
27/3 = 3x/3
