Not sure how to do this. would be appreciated! ! show work so i can better understand.

First student has a 1 minute head start at .20 miles per minute.
This is a distance of .2 miles.
The second student has to make up this distance by running at .25 miles per minute.  This produces a net gain on the first student by
(.25 -.20) = .05 miles per minute.

So how long does it take to run .20 miles at .05 miles per hour?
.2 miles / .05 miles per minute = 4 minutes.