Applicable formular:
F = Gm1m2/d^2, where F = gravitational force, m1 & m2 = mass of the two bodies, G = Gravitational constant, d = distance between the bodies.
Substituting;
8.64*10^-8 = (6.67*10^-11*90*90)/d^2
d^2 = (6.67*10^-11*90^2)/(8.64*10^-8)
d = Sqrt [(6.67*10^-11*90^2)/(8.64*10^-8)] = 2.5 m
The two men are 2.5 m apart.
