What law states that gravity depends on mass and distance?

Newton's "Law" of Universal Gravitation.

It even tells how to use the numbers for masses and distances, and how to

calculate the exact strength and direction of gravity. A lot of the physical

properties of space are wrapped up in it, and it predicts the acceleration of

free fall and the elliptical orbits of the planets. It is a very complicated and

detailed Law, full of mysterious mathematical symbols.

Here it is:

F = G M1M2/R2

That's it !