SOLUTION: The Smiths are moving across the country. Mr. Smith leaves 4 hours before Mrs. Smith. If he averages 60 mph and she averages 80 mph, how long will it take Mrs. Smith to overtake

Question 1039828: The Smiths are moving across the country. Mr. Smith leaves 4 hours before Mrs. Smith. If he averages 60 mph and she averages 80 mph, how long will it take Mrs. Smith to overtake Mr. Smith?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
How much of a head start in miles did Mr. Smith have?

mi
------------------
Start a stopwatch when Mrs. Smith leaves. Let
= the time on the stopwatch in hrs when Mrs. Smith
catches up with Mr. Smith.
Let = the distance in miles that Mrs. Smith
travels until she overtakes Mr. Smith
------------------
Mr. Smith's equation:
(1)
Mrs. Smith's equation:
(2)
-------------------
Substitute (2) into (1)
(1)
(1)
(1)
Mrs. Smith overtakes Mr. Smith in 12 hrs
-------------------
check:
(2)
(2)
(2) mi
and
(1)
(1)
(1)
(1) mi
OK
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