SOLUTION: a car traveled at 1280 mi at a certain speed. if the speed had been 16mph faster, the trip would have been made in 4hr less time. find the speed.

Question 654575: a car traveled at 1280 mi at a certain speed. if the speed had been 16mph faster, the trip would have been made in 4hr less time. find the speed.
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the car's actual speed in mi/hr
Let = the car's actual time in hours
given:
(1)
(2)
----------------------------
(2)
(2)
Substitute (1) into (2)
(2)
(2)
And, from (1)
(1)
Plug this back into (2)
(2)
(2)
(2)
I can solve this by inspection
(2)
( ignore , can't have negative time )
Plug this result back into (1)
(1)
(1)
The car's speed is 64 mi/hr
check:
(2)
(2)
(2)
OK

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