math
posted by Sara! .
a round trip car ride took 12 hours. the first half of the trip took 7 hours at a rate of 4 miles per hour. what was the average rate of speed on the return trip?
how do i write this as an equation?

distance = rate * time
The distance for both directions are equal.
rate1 * time1 = rate2 * time2 
I think its 63 miles per hour.
How i got it:
12 hrs. minus 7 hrs. = 5hrs for the return trip.
45*7= r*5
315==r*5
315/5 = 63 miles per hour
(i think that 63 is the answer. im not sure)