Let's begin by stating that a mile is equal to 5,280 feet.
Since there are 60 minutes in an hour, and 60 seconds in a minute, there are 60*60=3600 seconds in an hour.
Now let's convert 64m/h to ft/s:
[tex]\frac{64m}{h}\cdot\frac{1h}{3600s}\cdot\frac{5280ft}{1m}=\frac{64\cdot5280ft}{3600s}=\frac{337920ft}{3600s}=93.86\ldots\frac{ft}{s}[/tex]In other words, 64m/h is equal to approximately 93.87ft/s.