Answer:
∠AGF and ∠FGE, or ∠BGC and ∠CGD
Explanation
complementary angles are any angles which add up to 90°. since ∠AGB is a right angle according to the diagram, and AGD as well as BGE are straight lines (assumption), ∠DGE is also equivalent to 90° (opposite angles).
thus, the sum of ∠AGE and ∠BGD would be 90° each, so we know that ∠AGF and ∠FGE or ∠BGC and ∠CGD each add up to 90°.
i hope this helps! :D