Answer:
m∠DGB = 108°
Step-by-step explanation:
Linear pair:
If the non-common arms of two adjacent angles form a straight line, then the adjacent angles are called linear pair and they add up to 180°.
m∠AGD + m∠DGB = 180° {Linear pair}
72 + m∠DGB = 180
m∠DGB = 180 - 72
m∠DGB = 108°
