Afactory produces 3/4 of a mile of thread every 1/4 of an hour. what is the unit rate of miles of thread per hour?

Isn’t this 12/4 of a mile of thread every hour? If the factory produces 3/4 of a mile of thread every 1/4 of an hour, then all you need to do is 3/4 x 4. 1/4 is like .25 so to make a whole number, you have to do .25 x4 which makes the whole. I don’t know if my explanation is correct or not but I do believe my answer is. (12/4 is 3)

9sandwiches per hour