Use the formulla d=rt. find t for r =48.3m/h and d=545.79m.

If you solve d = rt for t, you have t = d/r.  If we have values for d and r we will fill them into that equation and divide.  .  Setting that up so the meters cancel as they should looks like this: lets us divide as we need to and at the same time cancel out the distance, leaving us time in hours.  The t value then is 11.3 hours.