We want to determine the rate in miles per hour.
From the infomation given,
distance = 35 miles
time = 40 min
We would convert the time from minutes to hour. Recall,
60 minutes = 1 hour
40 minutes = x hour
By crossmultiplying,
60x = 40
x = 40/60 = 2/3 hour
This means that 40 minutes = 2/3 hour
Rate = distance/time
By substituting the values into the formula,
rate = 35/(2/3)
rate = 52.5
The 52.5 miles per hour