Translate the Given Formula to an English Phrase Using the Word

Short Answer

Translate the given formula to an English phrase using the word ʺvariesʺ.
- $$\mathrm { r } = \frac { \mathrm { d } } { \mathrm { t } } \text {, where } \mathrm { r } \text { is the rate by which distance } \mathrm { d } \text { is covered in time }$$