Question 416911
Everything you did up until the end was correct, but I think you lost track of units.
284 ft = 284 ft/(5280 ft/mi) = 0.0537878 miles.  Keeping the units in the calculation helps avoid confusion.
You are correct that t = d/r.
Using the value for r given in the problem and the distance in miles that we just calculated gives
t = 0.0537878 mi/(30 mi/hr) = 0.001793 hrs.
This is the time required in hrs.
Converting to seconds gives -> 0.001793 hr * 60 min/hr * 60 sec/min = 6.45 sec.
Notice that the hr and min cancel and we are left with secs.