10) because of the alternative exterior angle theorem angle 2 is the same as angle 8 and because of the vertical angles congruence theorem angles 2 and 4 are also the same so if angle 2 is the same as both 4 and 8,
then x=5 because 4x+57 =77
subtract 57 from both sides and 4x=20
divide both sides by 4 and x equals 5