Density is defined as the comparative ratio of a substance's

Density is defined as the comparative ratio of a substance's mass per unit volume.

The formula of density of a substance is as follows:

Density=\frac{Mass}{Volume}

Let the unit of mass be grams and that of volume be mL thus, unit of density will be g/mL. For density value x g/mL, there are x grams of substance in 1 mL volume. Thus, density is the comparative ratio of mass per unit volume of a substance.

they vary. it used to be meat, grain, bread, candy, beverages, donuts, and fruits/vegetables. now they added exercise in.