Answer:
17 1/4 miles per hour
Step-by-step explanation:
First let's convert the mixed number to a fraction so it is easier to work with:
5 3/4 = (5*4 + 3)/4 = 23/4 miles.
Because she travelled it in a third of an hour, she could do it 3 times in 1 hour.
Because of this to get speed we divide the distance by the time taken.
23/4 divided by 1/3 is the same as saying 23/4 times 3:
(3*23)/4 = 69/4 = 17 1/4 miles per hour
