The train is travelling at 80 miles per hour, this can be represented by 80mi/h
As the symbol suggests, you find the value of speed by dividing the amount of miles by the amount of hours.
Let S be speed, D be distance and T be time
we get S=D/T so we have also T=D/S
as such, the time to go 288 miles is simply:
[tex]T=\frac{288}{80}=3,6 hours[/tex]