Challenge Overview
Given a number of miles ran, and a time in `"MM:SS"` (minutes:seconds) it took to run those miles, return a string for the average time it took to run each mile in the format `"MM:SS"`.
Given a number of miles ran, and a time in "MM:SS" (minutes:seconds) it took to run those miles, return a string for the average time it took to run each mile in the format "MM:SS".
- Add leading zeros when needed.