What is the relationship between distance and mass in termsnof gravitational force

There is no relationship between distance and mass.  But the gravitational force
between two objects is related to both of those quantities.

-- The gravitational force between two objects is directly proportional to
the product of their masses.

-- The force is also inversely proportional to the square of the distance
between their centers.

Well,

I'm pretty sure you wanted how the distance between objects or the mass of two objects affects the gravitational force.

The Second Universal Law of Gravitation states that the gravitational force between two objects is directly proportional to the mass of the two objects. (mass)

The Third Universal Law of Gravitation is a bit more complex: The gravitational force between two objects is inversely proportional to the square of the distances between those two objects.  This means that if the initial distance between two objects is 1 unit, and the initial gravitational force between those two objects is 1 unit, and then the distance between the two objects is halved, then the gravitational force will increase by the square of 2, or 4 units.  So the final distance will be 0.5 units and the final gravitational force will be 5 units.

Independent variable is something that is changed in a experiment.