1. **Problem Statement:** We have polygon ABCD reflected about the y-axis to form polygon EFGD. Given angles at vertices A (120°) and G (60°), and right angles at B, C, F, and G, we need to find the value of angle $k$ at vertex D. 2. **Reflection Properties:** Reflection about the y-axis changes the sign of the x-coordinate but preserves distances and angles. The reflected polygon EFGD is congruent to ABCD, but mirrored. 3. **Key Observations:** - Point D lies on the y-axis, so it is invariant under reflection. - Angle at A is 120°, so its reflected angle at E is also 120°. - Angle at G is 60°, corresponding to angle at C. - Angles at B and C are right angles, so angles at F and G are also right angles. 4. **Angle Sum at Vertex D:** Since polygons ABCD and EFGD share vertex D, the angles adjacent at D from both polygons sum to 360° around point D. 5. **Calculating $k$:** - Angle at A is 120°, so angle at E is 120°. - Angle at G is 60°. - The right angles at B, C, F, and G do not affect angle $k$ directly. - The sum of angles around point D is 360°, so $$k + 120 + 60 + 120 = 360$$ where 120 and 60 are angles adjacent to $k$ at D from polygons. 6. **Simplify:** $$k + 300 = 360$$ $$k = 360 - 300 = 60$$ 7. **Answer:** The value of $k$ is 60°. **Final answer:** $k = 60$° (option b).