She drove 5 hours you needed to divide 225 miles by 45 miles per hour then you get 5 hours that she drived.
Formula
d = r * t
d = distance
r = speed or rate of travel
t = time taken to travel
Givens
d = 225 miles
r = 45 miles / hour
t = ??
Substitute
d = r * t
225 miles = 45mph * t
225 / 45 = t
t = 5
Answer: She was on the road for 5 hours
