What formula relates mass volume and density?

The formula that relates the 3 variables, namely: mass, volume, and density is: Density = mass / volume.

Let us identify each variable:

Density - more accurately called the volumetric mass density of a substance is its mass per unit volume. It is a key concept that examines how materials communicate in a lot of things, i. e weather, material sciences, engineering, and other fields of science.

Mass - defined as a property of a physical body in Physics, and when a net force is applied, it results to the measure of a specific object’s resistance to acceleration.

Volume - contained or occupied by the space of a substance or shape (either by a solid, liquid, gas or plasma state)