[tex]321.5\ kmph\approx\boxed{199.770777\ mph}[/tex]
By the way, Google has a built in calculator. You can just type in "321.5 kmph in mph" and it will come up with this answer.
You could also use the fact that [tex]1\ km\approx0.621371\ mi[/tex],
According to the properties of equality, if you have two equal expressions and you change them in the same way, the results wil also be equal.
So that means we can multiply each side by 321.5 and get our answer above.
