Explanation:
Using properties of 30-60-90 triangles, the distance from the vase to the mirror is 2/√3, and the distance from the mirror to the girl is also 2/√3. So the light travels a total distance of 4/√3 meters.
t = d / v
t = (4/√3 m) / (3×10⁸ m/s)
t = 7.7×10⁻⁹ s
