One morning, Justin drove 5 hours before stopping to eat lunch at Chick-fil-A. After lunch, he increased his speed by 10 mph. If he completed a 230-mile trip in 7 hours of driving time, how fast did he drive in the morning? _____mph
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One morning, Justin drove 5 hours before stopping to eat lunch at Chick-fil-A. After lunch, he increased his speed by 10 mph. If he completed a 230-mile trip in 7 hours of driving time, how fast did he drive in the morning?
_____mph
Let x = "how fast did he drive in the morning".
Then his speed after lunch was (x+10)mph.
The equation is 5x + (10-5)*(x+10) = 230 miles.
5x + 2*(x+10) = 230 5x + 2x + 20 = 230 7x = 230-20= 210 ====> x = 210/7 = 30 miles per hour was his speed in the morning.
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