Answer:
a) GF = EH = 8
b) Angle G = Angle E = 60°
c, d) Angle H = Angle F = 180° - Angle E = 120°
To check the result: the sum of all angles in a parallelogram is equal to 360°:
Angle E + Angle F + Angle G + Angle H = 60 + 120 + 60 + 120 = 180 + 180 = 360°