Substitute to find the value of each expression.
Travel Time. The length of a flight from Seattle, Washington, to St. Paul, Minnesota, is approximately $1400 \mathrm{mi} .$ The time, in hours, for the flight is
$$
\frac{1400}{v}
$$
where $v$ is the velocity, in miles per hour. How long will a flight take at a velocity of $400 \mathrm{mph} ?$