A unit rate means blank per something. In this case we need to find miles per hr, as the unit rate. To do this we have to divide the amount of miles ()100) by the amount of hrs (4). The answer will be the amount of miles per hr. Then we will heck our work. Lets do it:-
100 ÷ 4 = 25
25 miles per hr.
CHECK OUR WORK:-
25 × 4 = 100
We were RIGHT!!
So, your unit rate for "100 miles per hr" is 25 miles per hr.
Hope I helped ya!! xD