It follows, for example, that the ratio of two extensive properties is an intensive property. To illustrate, consider a system having a certain mass, formula_10, and volume, formula_11. The density, formula_12 is equal to mass (extensive) divided by volume (extensive): formula_13. If the system is scaled by the factor formula_5, then the mass and volume become formula_15 and formula_16, and the density becomes formula_17; the two formula_5s cancel, so this could be written mathematically as formula_19, which is analogous to the equation for formula_1 above.