If the distance between two masses is doubled,the gravitational attraction between them

If the masses of two point objects are tripled and the distance between them is doubled,then the gravitational force of attraction between them will increase by .......... $\%$

The mass of the moon is about $1.2\%$ of the mass of the earth. Compared to the gravitational force the earth exerts on the moon,the gravitational force the moon exerts on the earth:

Two spheres of masses $m$ and $M$ are situated in air and the gravitational force between them is $F.$ The space around the masses is now filled with a liquid of specific gravity $3.$ The gravitational force will now be

Explain the principle of superposition for gravitational force.

Two point masses $A$ and $B$ having masses in the ratio $4 : 3$ are separated by a distance of $1\, m$. When another point mass $C$ of mass $M$ is placed in between $A$ and $B$,the gravitational force between $A$ and $C$ is $\frac{1}{3}$ of the gravitational force between $B$ and $C$. Then the distance of $C$ from $A$ is: