Answer:
60 mph
Step-by-step explanation:
We don't know how far Jimmy drives in each direction. Let this distance be d. Then, d = rate * time, and d = r(2 hours) (where r represents his speed while driving to the ferry).
But it's also true that d = (r - 20 mph)(3 hours).
Equating d = r(2 hours) and d = (r - 20 mph)(3 hours), we get:
r(2) = (r - 20)(3), or 2r = 3r - 60.
Subtracting 2r from both sides yields 0 = r - 60, so that r = 60 mph.
Jimmy averaged 60 mph on the outbound trip.
