After some research and studying the graph you posted with your question, there are many reasons why all four latitudes have the same number of hours of daylight on March 20th and also September 22nd.
Some of the reasons are:
These two dates are equinoxes, the sun's direct rays are over the equator, and the Earth's North Pole is not is not tilted toward or away from the Sun on those specific dates. Any of these answers are acceptable for the question you asked.
Answer:
As Earth rotates, different parts of Earth receive sunlight or darkness, giving us day and night. As your location on Earth rotates into sunlight, you see the sun rise. ... Since different parts of Earth enter and exit daylight at different times, we need different time zones.
It's 2:45 PM here
Answer:
The 50º West meridian is an imaginary line that crosses from the north pole to the south pole, passing through the center of Greenland and Brazil. Both nations, in the part of the territory that this imaginary line crosses, have a time zone of -3 UTC.
In turn, the 45º East meridian also goes from the north pole to the south pole, but this passes through the eastern part of the European continent, the Caucasus, the Arabian Peninsula and the Somali Peninsula, as well as through the center of Madagascar, regions that have a time zone of +3 UTC.
Therefore, if it were 12 noon at the 50º West meridian, it would be 6 PM at the 45º East meridian.
