The center of a moon of mass m is a distance d from the center of a planet of mass m. at some distance x from the center of the planet, along a line connecting the centers of planet and moon, the net force on an object will be zero.
(a) derive an expression for x.
(b) if the net force is zero a distance 2/3 d from the planet, what is the ratio r of the mass of the planet to the mass of the moon, m/m?