3 Two planets have masses M and m, and the ratio M/m=25. The distance between the planets is R. The point P is between the planets, and the distance between M and P is x. At P, the gravitational force on an object due to M and m are equal in magnitude. The value of x is (A)5R/6 (B)25R/36 (C)R/25 (D)6R/5 (E)none of these