A plane travels at 213 miles per hour. Work out an estimate for how long, in seconds, the plane takes to travel one mile.

213 miles/hour speed = distance/time
round 213 to 200 as only an estimate;
s=200/1 hour = 200/3600 seconds (then divide by 200 to get time for 1 mile)s = 1/18
at this speed, the plane travels 1 mile per 18 seconds.