If an imaginary line segment is drawn between the centers of the earth and the moon, then the net gravitational force F acting on an object situated on this line segment is
F = −K/ x to the 2nd power + 0.012K / (239 − x) to hte 2nd power
where K > 0 is a constant and x is the distance of the object from the center of the earth, measured in thousands of miles.

How far from the center of the earth is the "dead spot" where no net gravitational force acts upon the object? (Express your answer to the nearest thousand miles. Hint: The distance from the earth to the moon is approximately 239 thousand miles.)
thousand miles