John R. answered • 03/03/13

Physics and Math Tutor – Kind, Easy-going, Patient

We know from the first part that the distance is equal to the speed multiplied by the time

d = st, or d = (45 mi/hr)t

we also know from the last part this same distance is

d = (60 mi/hr)(43 mi - 10 mi - t), or (60 mi/hr)(33 hr - t).

Now elliminate the d

(45 mi/hr)t = (60 mi/hr)(33 hr - t)

and solve for t.

Note: In professional work it is always a good idea to keep track of the units this way (they operate mathematically the same way as variables). But for this math problem it may be best to drop them. Do what's best for you though.