Answer
Explanation given below.
Work Step by Step
We rejected the negative solution, as $t$ represents time of flight. This time starts at $t=0$ (takeoff) and is positive thereon. A negative time makes no sense, as it is time before the actual flight.
The $t=-24$ would be 'interpreted' as:
24 hours ago, the plane was in the US, and due to a negative tailwind, it took 24 hours to fly in the opposite direction of the one it is pointing to, effectively flying backward to touch down in Mexico at time $t=0 $.
In other words, this is nonsense.
