Answer: 3 mph.
Because....
3/4 of a mile is 0.75 miles.
0.75 miles = 15 minutes
X = 15 * 1 / 0.75
X = 20 minutes takes a mile to travel
20 minutes = 1 mile
60 minutes = X
Clearing X would give:
X = 60/20
X = 3 miles per hour.
Luis rides 3 miles per hour.
* Hopefully this helps:) Mark me the brainliest!!!