SOLUTION: Bret drove for 4hrs on the freeway, then decreased his speed by 20mph and drove for 5more hours on a country road. If his total trip was 485miles, then what was his speed on the fr

Question 504099: Bret drove for 4hrs on the freeway, then decreased his speed by 20mph and drove for 5more hours on a country road. If his total trip was 485miles, then what was his speed on the freeway?
Answer by oberobic(2304) (Show Source): You can put this solution on YOUR website!
f = freeway speed
c = country road speed
.
4f + 5c = 485 miles
.
f = c+20
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substitute
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4(c+20) +5c = 485
4c +80 + 5c = 485
9c +80 = 485
9c = 405
c = 45 mph
.
f = 45+20
f = 65 mph
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Always check your work.
.
4f = 4(65) = 260 miles
5c = 5(45) = 225 miles
260+225 = 485 miles
Correct.
.
Re-read the question to make sure you answer it.
.
What was his speed on the freeway? 65 mph.
.
Done.

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