100 miles in 4 hours. The unit rate would be 25 miles per hour.
100miles / 4hrs = 25 miles per hour
Therefore, for every hour you travel, you will gain 25 miles. Or for every 25 miles you travel, you've spent 1 hour traveling it.
y = 25x
where y is the total miles traveled, 25 is the constant unit rate, and x is the number of hours traveled.
for example: you traveled for 8 hours and you want to know how long you've traveled while maintaining the rate of 25mph. Just use the formula
y = 25x
y = 25(8)
y = 200 miles. you have traveled 200 miles in 8 hours.