we know that
\(speed=\frac{distance}{time}\)
Solve for the time
\(time=\frac{distance}{speed}\)
in this problem
\(speed=55\frac{miles}{hour} \\ \\ distance=310 miles\)
substitute in the formula above
\(time=\frac{310}{55} \\ \\ time=5.64\ hours\)
convert to minutes
\(5.64*60=338.4\ minutes =338\ minutes\)
therefore
the answer is
\(338\ minutes\)