SOLUTION: If it took Billy an hour to race over to his girlfriend�s house but two hours if he went 20 mph slower, how far away does Billy�s girlfriend live?

Question 1079833: If it took Billy an hour to race over to his girlfriend�s house but two hours if he went 20 mph slower, how far away does Billy�s girlfriend live?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the distance to his girlfriend's house
Let = his running speed in mi/hr
(1)
(2)
-----------------------
Plug (1) into (2)
(2)
(2)
(2)
-----------------------
Plug this result into (1)
(1)
(1)
His girlfriend lives 40 mi away
----------------------------
check:
(2)
(2)
(2)
(2) mi
OK
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