Let W be the man's speed while walking through the country
at 27 mph he will take 9/27=1/3 hours = 20 min to ride back the nine miles by car
so he must have hiked for 3h20m - 20m = 3 hours
mph,as the name suggests, is miles divided per hours:
so we have:
W= 9/3=3mph
his walking rate/speed/velocity is 3 miles per hour