The value of x in the diagram is 80 because vertical opposite angles are equal.
What is the value of x?
(x + 60)° = (2x - 20)°
vertical opposite angles are equal
x + 60 = 2x - 20
combine like terms
60 + 20 = 2x - x
80 = x
Check:
(x + 60)°
= 80 + 60
= 140°
(2x - 20)°
= 2(80) - 20
= 160 - 20
= 140°
Therefore, each of the angles measures 140°