Final answer:
Angle BGH is congruent to angle CHF, so angle BGH is also 122°.
Step-by-step explanation:
To find the size of angle BGH, we need to use the opposite angles theorem. According to this theorem, when two parallel lines are intersected by a transversal, the angles on the same side of the transversal and on the same side of the parallel lines are called corresponding angles and they are congruent. Therefore, angle BGH is congruent to angle CHF, which is 122°. So, the size of angle BGH is also 122°.