Question 353630
Hi,
Let x be the time at 70mph.  Then (7hr-x) would be the time left to traved at 10mph
d = r*t
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question states
70t + 10(7hr - t) = 250mi
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simplify and solve
70t + 70hr - 10t = 250mi
60t = 180mi
t = 3 hrs  (time driving at 70mph)
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4hr would be the ime left to be driving at the 10mph reduced speed
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check your answer
210mi + 40mi = 250 mi