Question 153613
Jay, you are right to question your answer!
The answer is you must use consistent units.  In other words, don't mix feet and miles or hours and seconds.
Since your problem asks "...how many seconds..." you need to convert the speed from miles per hour to feet per second.
You general approach is good!
Use: {{{d = rt}}}
Let's convert 90 mph to x ft/sec. As you know, there are 5,280 feet in one mile and there are 3600 seconds in one hour, multiply the 90 mph by 5,280 feet per mile and 1 hour by 3600 secs per hour to get:
90 mph = 132 ft/sec.
So, {{{t = d/r}}}
{{{t = 60.5/132}}}
{{{t = 0.45833}}}seconds (approximately)