Answer: (67/24, 0)
67/24 = 2.791667 approximately
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Step-by-step explanation
The mystery point is of the form (x,0) where x is some real number. Likely it's some number between -4 and 8 which are the x coordinates of the given points.
We know the y coordinate is 0 because this mystery point is on the x-axis.
Let's compute the distance from (8,-10) to (x,0)

Then we'll need the distance expression from (x,0) to (-4,9)

If the mystery point (x,0) is equidistant from (8,-10) and (-4,9), then those distance expressions we just calculated must be equal to one another.

Therefore the mystery point is located at approximately (2.791667, 0)
Round that approximate value however needed.
I recommend using GeoGebra to help verify the answer.