In this case you have:
[tex] \frac{miles}{minute} [/tex]
An hour has sixty minutes.
[tex] \frac{60 minutes}{1 hour}[/tex]
You must multiply by this equality.
[tex](\frac{miles}{minute})(\frac{60 minutes}{1 hour})=\frac{(miles)(60 minutes)}{ (minute)(hour)}=\frac{(miles)(60)}{(hour)}[/tex]
You must multiply by 60 and you can convert miles per minute to miles per hour.
